51136921 has 4 divisors (see below), whose sum is σ = 55785744. Its totient is φ = 46488100.

The previous prime is 51136919. The next prime is 51136951. The reversal of 51136921 is 12963115.

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 51136921 - 2¹ = 51136919 is a prime.

It is a super-2 number, since 2×51136921² = 5229969378720482, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 51136921.

It is not an unprimeable number, because it can be changed into a prime (51136951) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 2324395 + ... + 2324416.

It is an arithmetic number, because the mean of its divisors is an integer number (13946436).

Almost surely, 2^51136921 is an apocalyptic number.

It is an amenable number.

51136921 is a deficient number, since it is larger than the sum of its proper divisors (4648823).

51136921 is a wasteful number, since it uses less digits than its factorization.

51136921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4648822.

The product of its digits is 1620, while the sum is 28.

The square root of 51136921 is about 7151.0083904300. The cubic root of 51136921 is about 371.1745509060.

The spelling of 51136921 in words is "fifty-one million, one hundred thirty-six thousand, nine hundred twenty-one".