21015995 has 96 divisors (see below), whose sum is σ = 37946880. Its totient is φ = 10782720.

The previous prime is 21015971. The next prime is 21016007. The reversal of 21015995 is 59951012.

It is not a de Polignac number, because 21015995 - 2¹⁸ = 20753851 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1106096 + ... + 1106114.

It is an arithmetic number, because the mean of its divisors is an integer number (395280).

Almost surely, 2^21015995 is an apocalyptic number.

21015995 is a deficient number, since it is larger than the sum of its proper divisors (16930885).

21015995 is a wasteful number, since it uses less digits than its factorization.

21015995 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85 (or 72 counting only the distinct ones).

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

The square root of 21015995 is about 4584.3205603448. The cubic root of 21015995 is about 275.9624458811.

The spelling of 21015995 in words is "twenty-one million, fifteen thousand, nine hundred ninety-five".