21015793 has 4 divisors (see below), whose sum is σ = 21121600. Its totient is φ = 20909988.

The previous prime is 21015773. The next prime is 21015803. The reversal of 21015793 is 39751012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21015793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21015703) 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, 52605 + ... + 53002.

It is an arithmetic number, because the mean of its divisors is an integer number (5280400).

Almost surely, 2^21015793 is an apocalyptic number.

It is an amenable number.

21015793 is a deficient number, since it is larger than the sum of its proper divisors (105807).

21015793 is a wasteful number, since it uses less digits than its factorization.

21015793 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 105806.

The product of its (nonzero) digits is 1890, while the sum is 28.

The square root of 21015793 is about 4584.2985286737. The cubic root of 21015793 is about 275.9615617197.

The spelling of 21015793 in words is "twenty-one million, fifteen thousand, seven hundred ninety-three".