21764513 has 2 divisors, whose sum is σ = 21764514. Its totient is φ = 21764512.

The previous prime is 21764497. The next prime is 21764537. The reversal of 21764513 is 31546712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13337104 + 8427409 = 3652^2 + 2903^2 .

It is a cyclic number.

It is not a de Polignac number, because 21764513 - 2⁴ = 21764497 is a prime.

It is a super-2 number, since 2×21764513² = 947388052254338, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21764543) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10882256 + 10882257.

It is an arithmetic number, because the mean of its divisors is an integer number (10882257).

Almost surely, 2^21764513 is an apocalyptic number.

It is an amenable number.

21764513 is a deficient number, since it is larger than the sum of its proper divisors (1).

21764513 is an equidigital number, since it uses as much as digits as its factorization.

21764513 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5040, while the sum is 29.

The square root of 21764513 is about 4665.2452239941. The cubic root of 21764513 is about 279.2005811722.

The spelling of 21764513 in words is "twenty-one million, seven hundred sixty-four thousand, five hundred thirteen".