51539021 has 4 divisors (see below), whose sum is σ = 53779872. Its totient is φ = 49298172.

The previous prime is 51538997. The next prime is 51539027. The reversal of 51539021 is 12093515.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51539021 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51539027) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1120391 + ... + 1120436.

It is an arithmetic number, because the mean of its divisors is an integer number (13444968).

Almost surely, 2^51539021 is an apocalyptic number.

It is an amenable number.

51539021 is a deficient number, since it is larger than the sum of its proper divisors (2240851).

51539021 is a wasteful number, since it uses less digits than its factorization.

51539021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2240850.

The product of its (nonzero) digits is 1350, while the sum is 26.

The square root of 51539021 is about 7179.0682543071. The cubic root of 51539021 is about 372.1448856565.

The spelling of 51539021 in words is "fifty-one million, five hundred thirty-nine thousand, twenty-one".