21985740 has 72 divisors (see below), whose sum is σ = 76221600. Its totient is φ = 5025024.

The previous prime is 21985703. The next prime is 21985753. The reversal of 21985740 is 4758912.

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

It is a junction number, because it is equal to n+sod(n) for n = 21985695 and 21985704.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7465 + ... + 9984.

Almost surely, 2^21985740 is an apocalyptic number.

21985740 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21985740 is an abundant number, since it is smaller than the sum of its proper divisors (54235860).

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

21985740 is a wasteful number, since it uses less digits than its factorization.

21985740 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17471 (or 17466 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 36.

The square root of 21985740 is about 4688.8953923072. The cubic root of 21985740 is about 280.1433789487.

The spelling of 21985740 in words is "twenty-one million, nine hundred eighty-five thousand, seven hundred forty".