21398499 has 10 divisors (see below), whose sum is σ = 31965780. Its totient is φ = 14265612.

The previous prime is 21398497. The next prime is 21398513. The reversal of 21398499 is 99489312.

It is not a de Polignac number, because 21398499 - 2¹ = 21398497 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21398497) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 132009 + ... + 132170.

It is an arithmetic number, because the mean of its divisors is an integer number (3196578).

Almost surely, 2^21398499 is an apocalyptic number.

21398499 is a deficient number, since it is larger than the sum of its proper divisors (10567281).

21398499 is an equidigital number, since it uses as much as digits as its factorization.

21398499 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 264191 (or 264182 counting only the distinct ones).

The product of its digits is 139968, while the sum is 45.

The square root of 21398499 is about 4625.8511649209. The cubic root of 21398499 is about 277.6266186234.

The spelling of 21398499 in words is "twenty-one million, three hundred ninety-eight thousand, four hundred ninety-nine".