21751369 has 2 divisors, whose sum is σ = 21751370. Its totient is φ = 21751368.

The previous prime is 21751351. The next prime is 21751391. The reversal of 21751369 is 96315712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13838400 + 7912969 = 3720^2 + 2813^2 .

It is a cyclic number.

It is not a de Polignac number, because 21751369 - 2⁵ = 21751337 is a prime.

It is a super-2 number, since 2×21751369² = 946244106748322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21751339) 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, 10875684 + 10875685.

It is an arithmetic number, because the mean of its divisors is an integer number (10875685).

Almost surely, 2^21751369 is an apocalyptic number.

It is an amenable number.

21751369 is a deficient number, since it is larger than the sum of its proper divisors (1).

21751369 is an equidigital number, since it uses as much as digits as its factorization.

21751369 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11340, while the sum is 34.

The square root of 21751369 is about 4663.8362964409. The cubic root of 21751369 is about 279.1443650212.

The spelling of 21751369 in words is "twenty-one million, seven hundred fifty-one thousand, three hundred sixty-nine".