51561966 has 16 divisors (see below), whose sum is σ = 103287888. Its totient is φ = 17160000.

The previous prime is 51561919. The next prime is 51561973. The reversal of 51561966 is 66916515.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2535 + ... + 10466.

It is an arithmetic number, because the mean of its divisors is an integer number (6455493).

Almost surely, 2^51561966 is an apocalyptic number.

51561966 is an abundant number, since it is smaller than the sum of its proper divisors (51725922).

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

51561966 is a wasteful number, since it uses less digits than its factorization.

51561966 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13667.

The product of its digits is 48600, while the sum is 39.

The square root of 51561966 is about 7180.6661250890. Note that the first 3 decimals coincide. The cubic root of 51561966 is about 372.2001033497.

It can be divided in two parts, 515 and 61966, that added together give a triangular number (62481 = T₃₅₃).

The spelling of 51561966 in words is "fifty-one million, five hundred sixty-one thousand, nine hundred sixty-six".