51520415021 has 4 divisors (see below), whose sum is σ = 52616594112. Its totient is φ = 50424235932.

The previous prime is 51520414997. The next prime is 51520415027. The reversal of 51520415021 is 12051402515.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12051402515 = 5 ⋅2410280503.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51520415021 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 (51520415027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 548089475 + ... + 548089568.

It is an arithmetic number, because the mean of its divisors is an integer number (13154148528).

Almost surely, 2^51520415021 is an apocalyptic number.

It is an amenable number.

51520415021 is a deficient number, since it is larger than the sum of its proper divisors (1096179091).

51520415021 is a wasteful number, since it uses less digits than its factorization.

51520415021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1096179090.

The product of its (nonzero) digits is 2000, while the sum is 26.

Adding to 51520415021 its reverse (12051402515), we get a palindrome (63571817536).

The spelling of 51520415021 in words is "fifty-one billion, five hundred twenty million, four hundred fifteen thousand, twenty-one".