21129394 has 24 divisors (see below), whose sum is σ = 37446192. Its totient is φ = 8863920.

The previous prime is 21129379. The next prime is 21129403. The reversal of 21129394 is 49392112.

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, 877 + ... + 6559.

It is an arithmetic number, because the mean of its divisors is an integer number (1560258).

Almost surely, 2^21129394 is an apocalyptic number.

21129394 is a deficient number, since it is larger than the sum of its proper divisors (16316798).

21129394 is a wasteful number, since it uses less digits than its factorization.

21129394 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5722 (or 5709 counting only the distinct ones).

The product of its digits is 3888, while the sum is 31.

The square root of 21129394 is about 4596.6720570430. The cubic root of 21129394 is about 276.4579057746.

The spelling of 21129394 in words is "twenty-one million, one hundred twenty-nine thousand, three hundred ninety-four".