21311715 has 16 divisors (see below), whose sum is σ = 34580736. Its totient is φ = 11205600.

The previous prime is 21311701. The next prime is 21311729. The reversal of 21311715 is 51711312.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21311701) and next prime (21311729).

It is not a de Polignac number, because 21311715 - 2⁵ = 21311683 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21311691 and 21311700.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 8941 + ... + 11070.

It is an arithmetic number, because the mean of its divisors is an integer number (2161296).

Almost surely, 2^21311715 is an apocalyptic number.

21311715 is a deficient number, since it is larger than the sum of its proper divisors (13269021).

21311715 is a wasteful number, since it uses less digits than its factorization.

21311715 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20090.

The product of its digits is 210, while the sum is 21.

The square root of 21311715 is about 4616.4613071053. The cubic root of 21311715 is about 277.2507948578.

The spelling of 21311715 in words is "twenty-one million, three hundred eleven thousand, seven hundred fifteen".