21375660 has 24 divisors (see below), whose sum is σ = 59852016. Its totient is φ = 5700160.

The previous prime is 21375659. The next prime is 21375661. The reversal of 21375660 is 6657312.

It is an interprime number because it is at equal distance from previous prime (21375659) and next prime (21375661).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is not an unprimeable number, because it can be changed into a prime (21375661) by changing a digit.

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, 178071 + ... + 178190.

It is an arithmetic number, because the mean of its divisors is an integer number (2493834).

Almost surely, 2^21375660 is an apocalyptic number.

21375660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21375660 is an abundant number, since it is smaller than the sum of its proper divisors (38476356).

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

21375660 is a wasteful number, since it uses less digits than its factorization.

21375660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 356273 (or 356271 counting only the distinct ones).

The product of its (nonzero) digits is 7560, while the sum is 30.

The square root of 21375660 is about 4623.3818791011. The cubic root of 21375660 is about 277.5278115134.

The spelling of 21375660 in words is "twenty-one million, three hundred seventy-five thousand, six hundred sixty".