21357451 has 2 divisors, whose sum is σ = 21357452. Its totient is φ = 21357450.

The previous prime is 21357443. The next prime is 21357461. The reversal of 21357451 is 15475312.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21357451 - 2³ = 21357443 is a prime.

It is a super-2 number, since 2×21357451² = 912281426434802, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21357431) 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, 10678725 + 10678726.

It is an arithmetic number, because the mean of its divisors is an integer number (10678726).

Almost surely, 2^21357451 is an apocalyptic number.

21357451 is a deficient number, since it is larger than the sum of its proper divisors (1).

21357451 is an equidigital number, since it uses as much as digits as its factorization.

21357451 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4200, while the sum is 28.

The square root of 21357451 is about 4621.4122300440. The cubic root of 21357451 is about 277.4489844806.

The spelling of 21357451 in words is "twenty-one million, three hundred fifty-seven thousand, four hundred fifty-one".