21978676 has 24 divisors (see below), whose sum is σ = 40116384. Its totient is φ = 10526880.

The previous prime is 21978673. The next prime is 21978701. The reversal of 21978676 is 67687912.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21978673) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7911 + ... + 10321.

It is an arithmetic number, because the mean of its divisors is an integer number (1671516).

Almost surely, 2^21978676 is an apocalyptic number.

It is an amenable number.

21978676 is a deficient number, since it is larger than the sum of its proper divisors (18137708).

21978676 is a wasteful number, since it uses less digits than its factorization.

21978676 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2511 (or 2509 counting only the distinct ones).

The product of its digits is 254016, while the sum is 46.

The square root of 21978676 is about 4688.1420626939. The cubic root of 21978676 is about 280.1133724565.

The spelling of 21978676 in words is "twenty-one million, nine hundred seventy-eight thousand, six hundred seventy-six".