21515198 has 4 divisors (see below), whose sum is σ = 32272800. Its totient is φ = 10757598.

The previous prime is 21515171. The next prime is 21515203. The reversal of 21515198 is 89151512.

It is a semiprime because it is the product of two primes.

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 as a sum of consecutive naturals, namely, 5378798 + ... + 5378801.

It is an arithmetic number, because the mean of its divisors is an integer number (8068200).

Almost surely, 2^21515198 is an apocalyptic number.

21515198 is a deficient number, since it is larger than the sum of its proper divisors (10757602).

21515198 is a wasteful number, since it uses less digits than its factorization.

21515198 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10757601.

The product of its digits is 3600, while the sum is 32.

The square root of 21515198 is about 4638.4478007195. The cubic root of 21515198 is about 278.1303927415.

The spelling of 21515198 in words is "twenty-one million, five hundred fifteen thousand, one hundred ninety-eight".