21972887 has 4 divisors (see below), whose sum is σ = 22186320. Its totient is φ = 21759456.

The previous prime is 21972869. The next prime is 21972901. The reversal of 21972887 is 78827912.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21972887 - 2⁸ = 21972631 is a prime.

It is a super-2 number, since 2×21972887² = 965615526229538, 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 (21932887) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 106562 + ... + 106767.

It is an arithmetic number, because the mean of its divisors is an integer number (5546580).

Almost surely, 2^21972887 is an apocalyptic number.

21972887 is a deficient number, since it is larger than the sum of its proper divisors (213433).

21972887 is a wasteful number, since it uses less digits than its factorization.

21972887 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 213432.

The product of its digits is 112896, while the sum is 44.

The square root of 21972887 is about 4687.5246132687. The cubic root of 21972887 is about 280.0887771214.

The spelling of 21972887 in words is "twenty-one million, nine hundred seventy-two thousand, eight hundred eighty-seven".