21943980 has 48 divisors (see below), whose sum is σ = 68271840. Its totient is φ = 5851584.

The previous prime is 21943973. The next prime is 21944009. The reversal of 21943980 is 8934912.

21943980 is a `hidden beast` number, since 219 + 439 + 8 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19779 + ... + 20858.

It is an arithmetic number, because the mean of its divisors is an integer number (1422330).

Almost surely, 2^21943980 is an apocalyptic number.

21943980 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21943980 is an abundant number, since it is smaller than the sum of its proper divisors (46327860).

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

21943980 is a wasteful number, since it uses less digits than its factorization.

21943980 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40655 (or 40647 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 36.

The square root of 21943980 is about 4684.4402013474. The cubic root of 21943980 is about 279.9658972071.

The spelling of 21943980 in words is "twenty-one million, nine hundred forty-three thousand, nine hundred eighty".