21764459 has 2 divisors, whose sum is σ = 21764460. Its totient is φ = 21764458.

The previous prime is 21764453. The next prime is 21764467. The reversal of 21764459 is 95446712.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21764459 - 2¹⁶ = 21698923 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21764453) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10882229 + 10882230.

It is an arithmetic number, because the mean of its divisors is an integer number (10882230).

Almost surely, 2^21764459 is an apocalyptic number.

21764459 is a deficient number, since it is larger than the sum of its proper divisors (1).

21764459 is an equidigital number, since it uses as much as digits as its factorization.

21764459 is an evil number, because the sum of its binary digits is even.

The product of its digits is 60480, while the sum is 38.

The square root of 21764459 is about 4665.2394365134. The cubic root of 21764459 is about 279.2003502635.

The spelling of 21764459 in words is "twenty-one million, seven hundred sixty-four thousand, four hundred fifty-nine".