21976973 has 4 divisors (see below), whose sum is σ = 21987840. Its totient is φ = 21966108.

The previous prime is 21976967. The next prime is 21976979. The reversal of 21976973 is 37967912.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is an interprime number because it is at equal distance from previous prime (21976967) and next prime (21976979).

It is a cyclic number.

It is not a de Polignac number, because 21976973 - 2⁴ = 21976957 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 (21976979) 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, 1403 + ... + 6776.

It is an arithmetic number, because the mean of its divisors is an integer number (5496960).

Almost surely, 2^21976973 is an apocalyptic number.

It is an amenable number.

21976973 is a deficient number, since it is larger than the sum of its proper divisors (10867).

21976973 is an equidigital number, since it uses as much as digits as its factorization.

21976973 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10866.

The product of its digits is 142884, while the sum is 44.

The square root of 21976973 is about 4687.9604307204. The cubic root of 21976973 is about 280.1061374833.

The spelling of 21976973 in words is "twenty-one million, nine hundred seventy-six thousand, nine hundred seventy-three".