21966981 has 8 divisors (see below), whose sum is σ = 29362560. Its totient is φ = 14608032.

The previous prime is 21966961. The next prime is 21967019. The reversal of 21966981 is 18966912.

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

It is not a de Polignac number, because 21966981 - 2¹⁷ = 21835909 is a prime.

It is a super-2 number, since 2×21966981² = 965096508508722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21966961) 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, 7725 + ... + 10178.

It is an arithmetic number, because the mean of its divisors is an integer number (3670320).

Almost surely, 2^21966981 is an apocalyptic number.

It is an amenable number.

21966981 is a deficient number, since it is larger than the sum of its proper divisors (7395579).

21966981 is a wasteful number, since it uses less digits than its factorization.

21966981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18315.

The product of its digits is 46656, while the sum is 42.

The square root of 21966981 is about 4686.8946009058. The cubic root of 21966981 is about 280.0636802440.

The spelling of 21966981 in words is "twenty-one million, nine hundred sixty-six thousand, nine hundred eighty-one".