21099438 has 24 divisors (see below), whose sum is σ = 45899568. Its totient is φ = 7004832.

The previous prime is 21099427. The next prime is 21099451. The reversal of 21099438 is 83499012.

21099438 is a `hidden beast` number, since 210 + 9 + 9 + 438 = 666.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2506 + ... + 6962.

It is an arithmetic number, because the mean of its divisors is an integer number (1912482).

Almost surely, 2^21099438 is an apocalyptic number.

21099438 is an abundant number, since it is smaller than the sum of its proper divisors (24800130).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21099438 is a wasteful number, since it uses less digits than its factorization.

21099438 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4728 (or 4725 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 36.

The square root of 21099438 is about 4593.4124569866. The cubic root of 21099438 is about 276.3271954504.

The spelling of 21099438 in words is "twenty-one million, ninety-nine thousand, four hundred thirty-eight".