51561020 has 24 divisors (see below), whose sum is σ = 123746784. Its totient is φ = 17678016.

The previous prime is 51560987. The next prime is 51561031. The reversal of 51561020 is 2016515.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 51560983 and 51561001.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 184007 + ... + 184286.

It is an arithmetic number, because the mean of its divisors is an integer number (5156116).

Almost surely, 2^51561020 is an apocalyptic number.

It is an amenable number.

51561020 is an abundant number, since it is smaller than the sum of its proper divisors (72185764).

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

51561020 is a wasteful number, since it uses less digits than its factorization.

51561020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 368309 (or 368307 counting only the distinct ones).

The product of its (nonzero) digits is 300, while the sum is 20.

The square root of 51561020 is about 7180.6002534607. The cubic root of 51561020 is about 372.1978271018.

Adding to 51561020 its reverse (2016515), we get a palindrome (53577535).

The spelling of 51561020 in words is "fifty-one million, five hundred sixty-one thousand, twenty".