21464581 has 2 divisors, whose sum is σ = 21464582. Its totient is φ = 21464580.

The previous prime is 21464579. The next prime is 21464593. The reversal of 21464581 is 18546412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20848356 + 616225 = 4566^2 + 785^2 .

It is a cyclic number.

It is not a de Polignac number, because 21464581 - 2¹ = 21464579 is a prime.

It is a super-2 number, since 2×21464581² = 921456475011122, which contains 22 as substring.

Together with 21464579, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21464501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10732290 + 10732291.

It is an arithmetic number, because the mean of its divisors is an integer number (10732291).

Almost surely, 2^21464581 is an apocalyptic number.

It is an amenable number.

21464581 is a deficient number, since it is larger than the sum of its proper divisors (1).

21464581 is an equidigital number, since it uses as much as digits as its factorization.

21464581 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7680, while the sum is 31.

The square root of 21464581 is about 4632.9883444706. The cubic root of 21464581 is about 277.9121101321.

The spelling of 21464581 in words is "twenty-one million, four hundred sixty-four thousand, five hundred eighty-one".