21503732 has 24 divisors (see below), whose sum is σ = 39168360. Its totient is φ = 10317440.

The previous prime is 21503731. The next prime is 21503737. The reversal of 21503732 is 23730512.

It can be written as a sum of positive squares in 4 ways, for example, as 10784656 + 10719076 = 3284^2 + 3274^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21503698 and 21503707.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21503731) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22382 + ... + 23322.

It is an arithmetic number, because the mean of its divisors is an integer number (1632015).

Almost surely, 2^21503732 is an apocalyptic number.

It is an amenable number.

21503732 is a deficient number, since it is larger than the sum of its proper divisors (17664628).

21503732 is a wasteful number, since it uses less digits than its factorization.

21503732 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1171 (or 1169 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 23.

The square root of 21503732 is about 4637.2116621953. The cubic root of 21503732 is about 278.0809763590.

The spelling of 21503732 in words is "twenty-one million, five hundred three thousand, seven hundred thirty-two".