21081995 has 16 divisors (see below), whose sum is σ = 28274400. Its totient is φ = 14956800.

The previous prime is 21081979. The next prime is 21082003. The reversal of 21081995 is 59918012.

It is not a de Polignac number, because 21081995 - 2⁴ = 21081979 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 15 ways as a sum of consecutive naturals, for example, 2420 + ... + 6929.

It is an arithmetic number, because the mean of its divisors is an integer number (1767150).

Almost surely, 2^21081995 is an apocalyptic number.

21081995 is a deficient number, since it is larger than the sum of its proper divisors (7192405).

21081995 is a wasteful number, since it uses less digits than its factorization.

21081995 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9406.

The product of its (nonzero) digits is 6480, while the sum is 35.

The square root of 21081995 is about 4591.5133670719. The cubic root of 21081995 is about 276.2510274799.

The spelling of 21081995 in words is "twenty-one million, eighty-one thousand, nine hundred ninety-five".