21400375 has 8 divisors (see below), whose sum is σ = 26707824. Its totient is φ = 17120200.

The previous prime is 21400367. The next prime is 21400381. The reversal of 21400375 is 57300412.

It is not a de Polignac number, because 21400375 - 2³ = 21400367 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 85477 + ... + 85726.

It is an arithmetic number, because the mean of its divisors is an integer number (3338478).

Almost surely, 2^21400375 is an apocalyptic number.

21400375 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21400375 is a deficient number, since it is larger than the sum of its proper divisors (5307449).

21400375 is an equidigital number, since it uses as much as digits as its factorization.

21400375 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 171218 (or 171208 counting only the distinct ones).

The product of its (nonzero) digits is 840, while the sum is 22.

The square root of 21400375 is about 4626.0539339701. The cubic root of 21400375 is about 277.6347315338.

Adding to 21400375 its reverse (57300412), we get a palindrome (78700787).

The spelling of 21400375 in words is "twenty-one million, four hundred thousand, three hundred seventy-five".