51312021 has 4 divisors (see below), whose sum is σ = 68416032. Its totient is φ = 34208012.

The previous prime is 51311993. The next prime is 51312031. The reversal of 51312021 is 12021315.

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 51312021 - 2⁷ = 51311893 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51312031) 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, 8552001 + ... + 8552006.

It is an arithmetic number, because the mean of its divisors is an integer number (17104008).

Almost surely, 2^51312021 is an apocalyptic number.

It is an amenable number.

51312021 is a deficient number, since it is larger than the sum of its proper divisors (17104011).

51312021 is a wasteful number, since it uses less digits than its factorization.

51312021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17104010.

The product of its (nonzero) digits is 60, while the sum is 15.

The square root of 51312021 is about 7163.2409564386. The cubic root of 51312021 is about 371.5977195420.

Adding to 51312021 its reverse (12021315), we get a palindrome (63333336).

The spelling of 51312021 in words is "fifty-one million, three hundred twelve thousand, twenty-one".