51515015521 has 4 divisors (see below), whose sum is σ = 51520100544. Its totient is φ = 51509930500.

The previous prime is 51515015449. The next prime is 51515015537. The reversal of 51515015521 is 12551051515.

It is a happy number.

51515015521 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 not a de Polignac number, because 51515015521 - 2¹⁹ = 51514491233 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51515015551) 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, 2527285 + ... + 2547586.

It is an arithmetic number, because the mean of its divisors is an integer number (12880025136).

Almost surely, 2^51515015521 is an apocalyptic number.

It is an amenable number.

51515015521 is a deficient number, since it is larger than the sum of its proper divisors (5085023).

51515015521 is a wasteful number, since it uses less digits than its factorization.

51515015521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5085022.

The product of its (nonzero) digits is 6250, while the sum is 31.

The spelling of 51515015521 in words is "fifty-one billion, five hundred fifteen million, fifteen thousand, five hundred twenty-one".