21002375 has 16 divisors (see below), whose sum is σ = 26339040. Its totient is φ = 16720000.

The previous prime is 21002357. The next prime is 21002389. The reversal of 21002375 is 57320012.

It is a de Polignac number, because none of the positive numbers 2^k-21002375 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 49916 + ... + 50334.

It is an arithmetic number, because the mean of its divisors is an integer number (1646190).

Almost surely, 2^21002375 is an apocalyptic number.

21002375 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21002375 is a deficient number, since it is larger than the sum of its proper divisors (5336665).

21002375 is an equidigital number, since it uses as much as digits as its factorization.

21002375 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 835 (or 825 counting only the distinct ones).

The product of its (nonzero) digits is 420, while the sum is 20.

The square root of 21002375 is about 4582.8348213742. The cubic root of 21002375 is about 275.9028179523.

Adding to 21002375 its reverse (57320012), we get a palindrome (78322387).

The spelling of 21002375 in words is "twenty-one million, two thousand, three hundred seventy-five".