21002309975 has 24 divisors (see below), whose sum is σ = 26540890560. Its totient is φ = 16483259520.

The previous prime is 21002309941. The next prime is 21002309989. The reversal of 21002309975 is 57990320012.

It is not a de Polignac number, because 21002309975 - 2⁸ = 21002309719 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 276209 + ... + 343941.

It is an arithmetic number, because the mean of its divisors is an integer number (1105870440).

Almost surely, 2^21002309975 is an apocalyptic number.

21002309975 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21002309975 is a deficient number, since it is larger than the sum of its proper divisors (5538580585).

21002309975 is a wasteful number, since it uses less digits than its factorization.

21002309975 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67979 (or 67974 counting only the distinct ones).

The product of its (nonzero) digits is 34020, while the sum is 38.

Adding to 21002309975 its reverse (57990320012), we get a palindrome (78992629987).

The spelling of 21002309975 in words is "twenty-one billion, two million, three hundred nine thousand, nine hundred seventy-five".