21505152 has 32 divisors (see below), whose sum is σ = 57124080. Its totient is φ = 7168256.

The previous prime is 21505151. The next prime is 21505157. The reversal of 21505152 is 25150512.

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

It is not an unprimeable number, because it can be changed into a prime (21505151) 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, 27618 + ... + 28385.

Almost surely, 2^21505152 is an apocalyptic number.

It is an amenable number.

21505152 is an abundant number, since it is smaller than the sum of its proper divisors (35618928).

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

21505152 is an equidigital number, since it uses as much as digits as its factorization.

21505152 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56020 (or 56008 counting only the distinct ones).

The product of its (nonzero) digits is 500, while the sum is 21.

The square root of 21505152 is about 4637.3647689178. The cubic root of 21505152 is about 278.0870972546.

Adding to 21505152 its reverse (25150512), we get a palindrome (46655664).

The spelling of 21505152 in words is "twenty-one million, five hundred five thousand, one hundred fifty-two".