21152660 has 12 divisors (see below), whose sum is σ = 44420628. Its totient is φ = 8461056.

The previous prime is 21152657. The next prime is 21152669. The reversal of 21152660 is 6625112.

It can be written as a sum of positive squares in 2 ways, for example, as 13557124 + 7595536 = 3682^2 + 2756^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21152669) 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, 528797 + ... + 528836.

It is an arithmetic number, because the mean of its divisors is an integer number (3701719).

Almost surely, 2^21152660 is an apocalyptic number.

21152660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21152660 is an abundant number, since it is smaller than the sum of its proper divisors (23267968).

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

21152660 is a wasteful number, since it uses less digits than its factorization.

21152660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1057642 (or 1057640 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 21152660 is about 4599.2021047134. The cubic root of 21152660 is about 276.5593396704.

Adding to 21152660 its reverse (6625112), we get a palindrome (27777772).

It can be divided in two parts, 21152 and 660, that added together give a palindrome (21812).

The spelling of 21152660 in words is "twenty-one million, one hundred fifty-two thousand, six hundred sixty".