21095921 has 12 divisors (see below), whose sum is σ = 26771760. Its totient is φ = 16437960.

The previous prime is 21095911. The next prime is 21095927. The reversal of 21095921 is 12959012.

It is not a de Polignac number, because 21095921 - 2¹⁴ = 21079537 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21095927) 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 11 ways as a sum of consecutive naturals, for example, 19031 + ... + 20108.

It is an arithmetic number, because the mean of its divisors is an integer number (2230980).

Almost surely, 2^21095921 is an apocalyptic number.

It is an amenable number.

21095921 is a deficient number, since it is larger than the sum of its proper divisors (5675839).

21095921 is a wasteful number, since it uses less digits than its factorization.

21095921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39164 (or 39157 counting only the distinct ones).

The product of its (nonzero) digits is 1620, while the sum is 29.

The square root of 21095921 is about 4593.0296101811. The cubic root of 21095921 is about 276.3118412223.

The spelling of 21095921 in words is "twenty-one million, ninety-five thousand, nine hundred twenty-one".