51815700 has 90 divisors (see below), whose sum is σ = 167992286. Its totient is φ = 13815360.

The previous prime is 51815693. The next prime is 51815707. The reversal of 51815700 is 751815.

It is an interprime number because it is at equal distance from previous prime (51815693) and next prime (51815707).

It can be written as a sum of positive squares in 3 ways, for example, as 492804 + 51322896 = 702^2 + 7164^2 .

It is a tau number, because it is divible by the number of its divisors (90).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51815707) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 4902 + ... + 11298.

Almost surely, 2^51815700 is an apocalyptic number.

51815700 is a gapful number since it is divisible by the number (50) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 51815700, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (83996143).

51815700 is an abundant number, since it is smaller than the sum of its proper divisors (116176586).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

51815700 is a wasteful number, since it uses less digits than its factorization.

51815700 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6423 (or 6407 counting only the distinct ones).

The product of its (nonzero) digits is 1400, while the sum is 27.

The square root of 51815700 is about 7198.3123021997. The cubic root of 51815700 is about 372.8096309994.

The spelling of 51815700 in words is "fifty-one million, eight hundred fifteen thousand, seven hundred".