21976840 has 16 divisors (see below), whose sum is σ = 49447980. Its totient is φ = 8790720.

The previous prime is 21976831. The next prime is 21976847. The reversal of 21976840 is 4867912.

It can be written as a sum of positive squares in 2 ways, for example, as 19660356 + 2316484 = 4434^2 + 1522^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21976840.

It is not an unprimeable number, because it can be changed into a prime (21976847) 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, 274671 + ... + 274750.

Almost surely, 2^21976840 is an apocalyptic number.

21976840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21976840 is an abundant number, since it is smaller than the sum of its proper divisors (27471140).

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

21976840 is a wasteful number, since it uses less digits than its factorization.

21976840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 549432 (or 549428 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 37.

The square root of 21976840 is about 4687.9462454256. The cubic root of 21976840 is about 280.1055724344.

The spelling of 21976840 in words is "twenty-one million, nine hundred seventy-six thousand, eight hundred forty".