51557220 has 144 divisors (see below), whose sum is σ = 183822912. Its totient is φ = 11531520.

The previous prime is 51557189. The next prime is 51557221. The reversal of 51557220 is 2275515.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51557221) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 24739 + ... + 26741.

It is an arithmetic number, because the mean of its divisors is an integer number (1276548).

Almost surely, 2^51557220 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 51557220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (91911456).

51557220 is an abundant number, since it is smaller than the sum of its proper divisors (132265692).

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

51557220 is a wasteful number, since it uses less digits than its factorization.

51557220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2042 (or 2037 counting only the distinct ones).

The product of its (nonzero) digits is 3500, while the sum is 27.

The square root of 51557220 is about 7180.3356467508. The cubic root of 51557220 is about 372.1886833307.

The spelling of 51557220 in words is "fifty-one million, five hundred fifty-seven thousand, two hundred twenty".