15000021 has 12 divisors (see below), whose sum is σ = 21790080. Its totient is φ = 9943080.

The previous prime is 15000017. The next prime is 15000031. The reversal of 15000021 is 12000051.

It is a happy number.

It is not a de Polignac number, because 15000021 - 2² = 15000017 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

15000021 is a modest number, since divided by 21 gives 15 as remainder.

It is a junction number, because it is equal to n+sod(n) for n = 14999967 and 15000012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15000031) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 3045 + ... + 6266.

It is an arithmetic number, because the mean of its divisors is an integer number (1815840).

Almost surely, 2^15000021 is an apocalyptic number.

It is an amenable number.

15000021 is a deficient number, since it is larger than the sum of its proper divisors (6790059).

15000021 is a wasteful number, since it uses less digits than its factorization.

15000021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9496 (or 9493 counting only the distinct ones).

The product of its (nonzero) digits is 10, while the sum is 9.

The square root of 15000021 is about 3872.9860572948. The cubic root of 15000021 is about 246.6213225229.

Adding to 15000021 its reverse (12000051), we get a palindrome (27000072).

The spelling of 15000021 in words is "fifteen million, twenty-one", and thus it is an aban number and an uban number.