21745536 has 32 divisors (see below), whose sum is σ = 57762600. Its totient is φ = 7248384.

The previous prime is 21745531. The next prime is 21745543. The reversal of 21745536 is 63554712.

It is a tau number, because it is divible by the number of its divisors (32).

It is a hoax number, since the sum of its digits (33) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 21745497 and 21745506.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21745531) 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, 27931 + ... + 28698.

Almost surely, 2^21745536 is an apocalyptic number.

It is an amenable number.

21745536 is an abundant number, since it is smaller than the sum of its proper divisors (36017064).

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

21745536 is an equidigital number, since it uses as much as digits as its factorization.

21745536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56646 (or 56634 counting only the distinct ones).

The product of its digits is 25200, while the sum is 33.

The square root of 21745536 is about 4663.2109109497. The cubic root of 21745536 is about 279.1194103521.

It can be divided in two parts, 217 and 45536, that added together give a triangular number (45753 = T₃₀₂).

The spelling of 21745536 in words is "twenty-one million, seven hundred forty-five thousand, five hundred thirty-six".