21450015 has 20 divisors (see below), whose sum is σ = 38451864. Its totient is φ = 11439792.

The previous prime is 21449959. The next prime is 21450019. The reversal of 21450015 is 51005412.

It is not a de Polignac number, because 21450015 - 2⁷ = 21449887 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21450015.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21450019) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 26077 + ... + 26886.

Almost surely, 2^21450015 is an apocalyptic number.

21450015 is a deficient number, since it is larger than the sum of its proper divisors (17001849).

21450015 is an equidigital number, since it uses as much as digits as its factorization.

21450015 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52980 (or 52971 counting only the distinct ones).

The product of its (nonzero) digits is 200, while the sum is 18.

The square root of 21450015 is about 4631.4160901392. The cubic root of 21450015 is about 277.8492316033.

Adding to 21450015 its reverse (51005412), we get a palindrome (72455427).

The spelling of 21450015 in words is "twenty-one million, four hundred fifty thousand, fifteen".