51691578 has 16 divisors (see below), whose sum is σ = 103770720. Its totient is φ = 17165936.

The previous prime is 51691567. The next prime is 51691579. The reversal of 51691578 is 87519615.

It is a super-2 number, since 2×51691578² = 5344038472260168, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (51691579) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14400 + ... + 17627.

It is an arithmetic number, because the mean of its divisors is an integer number (6485670).

Almost surely, 2^51691578 is an apocalyptic number.

51691578 is an abundant number, since it is smaller than the sum of its proper divisors (52079142).

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

51691578 is a wasteful number, since it uses less digits than its factorization.

51691578 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32301.

The product of its digits is 75600, while the sum is 42.

The square root of 51691578 is about 7189.6855285889. The cubic root of 51691578 is about 372.5117105157.

The spelling of 51691578 in words is "fifty-one million, six hundred ninety-one thousand, five hundred seventy-eight".