51561537378 has 16 divisors (see below), whose sum is σ = 111055619136. Its totient is φ = 15865088400.

The previous prime is 51561537373. The next prime is 51561537409. The reversal of 51561537378 is 87373516515.

It is a happy number.

It is a super-2 number, since 2×51561537378² (a number of 22 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 51561537378.

It is not an unprimeable number, because it can be changed into a prime (51561537373) 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, 330522598 + ... + 330522753.

It is an arithmetic number, because the mean of its divisors is an integer number (6940976196).

Almost surely, 2^51561537378 is an apocalyptic number.

51561537378 is an abundant number, since it is smaller than the sum of its proper divisors (59494081758).

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

51561537378 is a wasteful number, since it uses less digits than its factorization.

51561537378 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 661045369.

The product of its digits is 2646000, while the sum is 51.

The spelling of 51561537378 in words is "fifty-one billion, five hundred sixty-one million, five hundred thirty-seven thousand, three hundred seventy-eight".