21764959 has 2 divisors, whose sum is σ = 21764960. Its totient is φ = 21764958.

The previous prime is 21764933. The next prime is 21765019. The reversal of 21764959 is 95946712.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21764959 - 2⁹ = 21764447 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21764929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10882479 + 10882480.

It is an arithmetic number, because the mean of its divisors is an integer number (10882480).

Almost surely, 2^21764959 is an apocalyptic number.

21764959 is a deficient number, since it is larger than the sum of its proper divisors (1).

21764959 is an equidigital number, since it uses as much as digits as its factorization.

21764959 is an evil number, because the sum of its binary digits is even.

The product of its digits is 136080, while the sum is 43.

The square root of 21764959 is about 4665.2930240232. The cubic root of 21764959 is about 279.2024882921.

The spelling of 21764959 in words is "twenty-one million, seven hundred sixty-four thousand, nine hundred fifty-nine".