51221688 has 64 divisors (see below), whose sum is σ = 146880000. Its totient is φ = 14581632.

The previous prime is 51221659. The next prime is 51221693. The reversal of 51221688 is 88612215.

It is a super-4 number, since 4×51221688⁴ (a number of 32 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 85213 + ... + 85811.

It is an arithmetic number, because the mean of its divisors is an integer number (2295000).

Almost surely, 2^51221688 is an apocalyptic number.

It is an amenable number.

51221688 is an abundant number, since it is smaller than the sum of its proper divisors (95658312).

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

51221688 is a wasteful number, since it uses less digits than its factorization.

51221688 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1124 (or 1120 counting only the distinct ones).

The product of its digits is 7680, while the sum is 33.

The square root of 51221688 is about 7156.9328626165. The cubic root of 51221688 is about 371.3795299015.

The spelling of 51221688 in words is "fifty-one million, two hundred twenty-one thousand, six hundred eighty-eight".