21957860 has 12 divisors (see below), whose sum is σ = 46111548. Its totient is φ = 8783136.

The previous prime is 21957857. The next prime is 21957877. The reversal of 21957860 is 6875912.

It can be written as a sum of positive squares in 2 ways, for example, as 14945956 + 7011904 = 3866^2 + 2648^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 548927 + ... + 548966.

It is an arithmetic number, because the mean of its divisors is an integer number (3842629).

Almost surely, 2^21957860 is an apocalyptic number.

21957860 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21957860 is an abundant number, since it is smaller than the sum of its proper divisors (24153688).

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

21957860 is a wasteful number, since it uses less digits than its factorization.

21957860 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1097902 (or 1097900 counting only the distinct ones).

The product of its (nonzero) digits is 30240, while the sum is 38.

The square root of 21957860 is about 4685.9214675451. The cubic root of 21957860 is about 280.0249127493.

The spelling of 21957860 in words is "twenty-one million, nine hundred fifty-seven thousand, eight hundred sixty".