51155550 has 120 divisors (see below), whose sum is σ = 150700176. Its totient is φ = 12821760.

The previous prime is 51155539. The next prime is 51155551. The reversal of 51155550 is 5555115.

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 (51155551) by changing a digit.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 68479 + ... + 69221.

Almost surely, 2^51155550 is an apocalyptic number.

51155550 is a gapful number since it is divisible by the number (50) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 51155550, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (75350088).

51155550 is an abundant number, since it is smaller than the sum of its proper divisors (99544626).

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

51155550 is a wasteful number, since it uses less digits than its factorization.

51155550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 784 (or 770 counting only the distinct ones).

The product of its (nonzero) digits is 3125, while the sum is 27.

The square root of 51155550 is about 7152.3108153939. The cubic root of 51155550 is about 371.2196179606.

The spelling of 51155550 in words is "fifty-one million, one hundred fifty-five thousand, five hundred fifty".