21400015 has 24 divisors (see below), whose sum is σ = 32175360. Its totient is φ = 13543488.

The previous prime is 21400003. The next prime is 21400031. The reversal of 21400015 is 51000412.

It is not a de Polignac number, because 21400015 - 2⁹ = 21399503 is a prime.

It is a super-3 number, since 3×21400015³ (a number of 23 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (13).

It is a plaindrome in base 16.

It is a junction number, because it is equal to n+sod(n) for n = 21399968 and 21400004.

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 23 ways as a sum of consecutive naturals, for example, 175 + ... + 6544.

It is an arithmetic number, because the mean of its divisors is an integer number (1340640).

Almost surely, 2^21400015 is an apocalyptic number.

21400015 is a deficient number, since it is larger than the sum of its proper divisors (10775345).

21400015 is a wasteful number, since it uses less digits than its factorization.

21400015 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6751 (or 6744 counting only the distinct ones).

The product of its (nonzero) digits is 40, while the sum is 13.

The square root of 21400015 is about 4626.0150237542. The cubic root of 21400015 is about 277.6331747221.

Adding to 21400015 its reverse (51000412), we get a palindrome (72400427).

The spelling of 21400015 in words is "twenty-one million, four hundred thousand, fifteen".