51585820 has 96 divisors (see below), whose sum is σ = 134882496. Its totient is φ = 16281600.

The previous prime is 51585791. The next prime is 51585823. The reversal of 51585820 is 2858515.

It is a happy number.

It is a super-2 number, since 2×51585820² = 5322193650144800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (34).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51585823) 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 31 ways as a sum of consecutive naturals, for example, 48090 + ... + 49150.

It is an arithmetic number, because the mean of its divisors is an integer number (1405026).

Almost surely, 2^51585820 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 51585820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (67441248).

51585820 is an abundant number, since it is smaller than the sum of its proper divisors (83296676).

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

51585820 is a wasteful number, since it uses less digits than its factorization.

51585820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1111 (or 1109 counting only the distinct ones).

The product of its (nonzero) digits is 16000, while the sum is 34.

The square root of 51585820 is about 7182.3269209916. The cubic root of 51585820 is about 372.2574912085.

The spelling of 51585820 in words is "fifty-one million, five hundred eighty-five thousand, eight hundred twenty".