21955871 has 12 divisors (see below), whose sum is σ = 26422920. Its totient is φ = 18169200.

The previous prime is 21955867. The next prime is 21955877. The reversal of 21955871 is 17855912.

It is not a de Polignac number, because 21955871 - 2² = 21955867 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21955877) 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, 6305 + ... + 9146.

It is an arithmetic number, because the mean of its divisors is an integer number (2201910).

Almost surely, 2^21955871 is an apocalyptic number.

21955871 is a deficient number, since it is larger than the sum of its proper divisors (4467049).

21955871 is a wasteful number, since it uses less digits than its factorization.

21955871 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15494 (or 15487 counting only the distinct ones).

The product of its digits is 25200, while the sum is 38.

The square root of 21955871 is about 4685.7092312691. The cubic root of 21955871 is about 280.0164573660.

The spelling of 21955871 in words is "twenty-one million, nine hundred fifty-five thousand, eight hundred seventy-one".