51388921 has 2 divisors, whose sum is σ = 51388922. Its totient is φ = 51388920.

The previous prime is 51388903. The next prime is 51388927. The reversal of 51388921 is 12988315.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 36481600 + 14907321 = 6040^2 + 3861^2 .

It is a cyclic number.

It is not a de Polignac number, because 51388921 - 2⁵ = 51388889 is a prime.

It is not a weakly prime, because it can be changed into another prime (51388927) 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 as a sum of consecutive naturals, namely, 25694460 + 25694461.

It is an arithmetic number, because the mean of its divisors is an integer number (25694461).

Almost surely, 2^51388921 is an apocalyptic number.

It is an amenable number.

51388921 is a deficient number, since it is larger than the sum of its proper divisors (1).

51388921 is an equidigital number, since it uses as much as digits as its factorization.

51388921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17280, while the sum is 37.

The square root of 51388921 is about 7168.6066289063. The cubic root of 51388921 is about 371.7832615173.

The spelling of 51388921 in words is "fifty-one million, three hundred eighty-eight thousand, nine hundred twenty-one".