21131895 has 32 divisors (see below), whose sum is σ = 36288000. Its totient is φ = 10468224.

The previous prime is 21131881. The next prime is 21131897. The reversal of 21131895 is 59813112.

It is not a de Polignac number, because 21131895 - 2¹⁴ = 21115511 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21131897) by changing a digit.

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 31 ways as a sum of consecutive naturals, for example, 14406 + ... + 15804.

It is an arithmetic number, because the mean of its divisors is an integer number (1134000).

Almost surely, 2^21131895 is an apocalyptic number.

21131895 is a deficient number, since it is larger than the sum of its proper divisors (15156105).

21131895 is a wasteful number, since it uses less digits than its factorization.

21131895 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1479.

The product of its digits is 2160, while the sum is 30.

The square root of 21131895 is about 4596.9440936344. The cubic root of 21131895 is about 276.4688130750.

The spelling of 21131895 in words is "twenty-one million, one hundred thirty-one thousand, eight hundred ninety-five".