21051959 has 4 divisors (see below), whose sum is σ = 21340416. Its totient is φ = 20763504.

The previous prime is 21051949. The next prime is 21051977. The reversal of 21051959 is 95915012.

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 21051959 - 2⁸ = 21051703 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 (21051949) 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, 144119 + ... + 144264.

It is an arithmetic number, because the mean of its divisors is an integer number (5335104).

Almost surely, 2^21051959 is an apocalyptic number.

21051959 is a deficient number, since it is larger than the sum of its proper divisors (288457).

21051959 is an equidigital number, since it uses as much as digits as its factorization.

21051959 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 288456.

The product of its (nonzero) digits is 4050, while the sum is 32.

The square root of 21051959 is about 4588.2413842343. The cubic root of 21051959 is about 276.1197714086.

The spelling of 21051959 in words is "twenty-one million, fifty-one thousand, nine hundred fifty-nine".