21053959 has 4 divisors (see below), whose sum is σ = 21083416. Its totient is φ = 21024504.

The previous prime is 21053941. The next prime is 21053969. The reversal of 21053959 is 95935012.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21053959 - 2⁷ = 21053831 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21053909) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13629 + ... + 15094.

It is an arithmetic number, because the mean of its divisors is an integer number (5270854).

Almost surely, 2^21053959 is an apocalyptic number.

21053959 is a deficient number, since it is larger than the sum of its proper divisors (29457).

21053959 is an equidigital number, since it uses as much as digits as its factorization.

21053959 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29456.

The product of its (nonzero) digits is 12150, while the sum is 34.

The square root of 21053959 is about 4588.4593274867. The cubic root of 21053959 is about 276.1285152038.

The spelling of 21053959 in words is "twenty-one million, fifty-three thousand, nine hundred fifty-nine".