21979480 has 32 divisors (see below), whose sum is σ = 50793840. Its totient is φ = 8553600.

The previous prime is 21979469. The next prime is 21979547. The reversal of 21979480 is 8497912.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5946 + ... + 8905.

Almost surely, 2^21979480 is an apocalyptic number.

21979480 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21979480 is an abundant number, since it is smaller than the sum of its proper divisors (28814360).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21979480 is a wasteful number, since it uses less digits than its factorization.

21979480 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14899 (or 14895 counting only the distinct ones).

The product of its (nonzero) digits is 36288, while the sum is 40.

The square root of 21979480 is about 4688.2278101645. The cubic root of 21979480 is about 280.1167880156.

The spelling of 21979480 in words is "twenty-one million, nine hundred seventy-nine thousand, four hundred eighty".