21751913 has 2 divisors, whose sum is σ = 21751914. Its totient is φ = 21751912.

The previous prime is 21751843. The next prime is 21751949. The reversal of 21751913 is 31915712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11202409 + 10549504 = 3347^2 + 3248^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21751913 is a prime.

It is equal to p_1374545 and since 21751913 and 1374545 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (21751963) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10875956 + 10875957.

It is an arithmetic number, because the mean of its divisors is an integer number (10875957).

Almost surely, 2^21751913 is an apocalyptic number.

It is an amenable number.

21751913 is a deficient number, since it is larger than the sum of its proper divisors (1).

21751913 is an equidigital number, since it uses as much as digits as its factorization.

21751913 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1890, while the sum is 29.

The square root of 21751913 is about 4663.8946171628. The cubic root of 21751913 is about 279.1466921279.

The spelling of 21751913 in words is "twenty-one million, seven hundred fifty-one thousand, nine hundred thirteen".