21956871 has 8 divisors (see below), whose sum is σ = 29415424. Its totient is φ = 14568120.

The previous prime is 21956863. The next prime is 21956887. The reversal of 21956871 is 17865912.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21956871 - 2³ = 21956863 is a prime.

It is a super-2 number, since 2×21956871² = 964208368221282, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21956801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16711 + ... + 17976.

It is an arithmetic number, because the mean of its divisors is an integer number (3676928).

Almost surely, 2^21956871 is an apocalyptic number.

21956871 is a deficient number, since it is larger than the sum of its proper divisors (7458553).

21956871 is a wasteful number, since it uses less digits than its factorization.

21956871 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34901.

The product of its digits is 30240, while the sum is 39.

The square root of 21956871 is about 4685.8159374862. The cubic root of 21956871 is about 280.0207085024.

The spelling of 21956871 in words is "twenty-one million, nine hundred fifty-six thousand, eight hundred seventy-one".