21352660 has 24 divisors (see below), whose sum is σ = 51246720. Its totient is φ = 7320864.

The previous prime is 21352651. The next prime is 21352687. The reversal of 21352660 is 6625312.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 76120 + ... + 76399.

It is an arithmetic number, because the mean of its divisors is an integer number (2135280).

Almost surely, 2^21352660 is an apocalyptic number.

21352660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21352660 is an abundant number, since it is smaller than the sum of its proper divisors (29894060).

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

21352660 is a wasteful number, since it uses less digits than its factorization.

21352660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 152535 (or 152533 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 25.

The square root of 21352660 is about 4620.8938529250. The cubic root of 21352660 is about 277.4282367255.

Adding to 21352660 its reverse (6625312), we get a palindrome (27977972).

The spelling of 21352660 in words is "twenty-one million, three hundred fifty-two thousand, six hundred sixty".