21057963 has 4 divisors (see below), whose sum is σ = 28077288. Its totient is φ = 14038640.

The previous prime is 21057943. The next prime is 21057979. The reversal of 21057963 is 36975012.

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 21057963 - 2¹⁰ = 21056939 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21057923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3509658 + ... + 3509663.

It is an arithmetic number, because the mean of its divisors is an integer number (7019322).

Almost surely, 2^21057963 is an apocalyptic number.

21057963 is a deficient number, since it is larger than the sum of its proper divisors (7019325).

21057963 is an equidigital number, since it uses as much as digits as its factorization.

21057963 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7019324.

The product of its (nonzero) digits is 11340, while the sum is 33.

The square root of 21057963 is about 4588.8956187736. The cubic root of 21057963 is about 276.1460186180.

The spelling of 21057963 in words is "twenty-one million, fifty-seven thousand, nine hundred sixty-three".