21973171 has 16 divisors (see below), whose sum is σ = 24893568. Its totient is φ = 19220800.

The previous prime is 21973169. The next prime is 21973181. The reversal of 21973171 is 17137912.

It is not a de Polignac number, because 21973171 - 2¹ = 21973169 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21973181) 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 15 ways as a sum of consecutive naturals, for example, 37140 + ... + 37726.

It is an arithmetic number, because the mean of its divisors is an integer number (1555848).

Almost surely, 2^21973171 is an apocalyptic number.

21973171 is a deficient number, since it is larger than the sum of its proper divisors (2920397).

21973171 is a wasteful number, since it uses less digits than its factorization.

21973171 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 722.

The product of its digits is 2646, while the sum is 31.

The square root of 21973171 is about 4687.5549063451. The cubic root of 21973171 is about 280.0899838338.

The spelling of 21973171 in words is "twenty-one million, nine hundred seventy-three thousand, one hundred seventy-one".