21735920 has 40 divisors (see below), whose sum is σ = 52737696. Its totient is φ = 8315648.

The previous prime is 21735919. The next prime is 21735937. The reversal of 21735920 is 2953712.

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4067 + ... + 7746.

Almost surely, 2^21735920 is an apocalyptic number.

21735920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21735920 is an abundant number, since it is smaller than the sum of its proper divisors (31001776).

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

21735920 is a wasteful number, since it uses less digits than its factorization.

21735920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11849 (or 11843 counting only the distinct ones).

The product of its (nonzero) digits is 3780, while the sum is 29.

The square root of 21735920 is about 4662.1797477146. The cubic root of 21735920 is about 279.0782615546.

The spelling of 21735920 in words is "twenty-one million, seven hundred thirty-five thousand, nine hundred twenty".