21399394 has 8 divisors (see below), whose sum is σ = 32966748. Its totient is φ = 10410480.

The previous prime is 21399353. The next prime is 21399401. The reversal of 21399394 is 49399312.

It can be written as a sum of positive squares in 2 ways, for example, as 17347225 + 4052169 = 4165^2 + 2013^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 144517 + ... + 144664.

Almost surely, 2^21399394 is an apocalyptic number.

21399394 is a deficient number, since it is larger than the sum of its proper divisors (11567354).

21399394 is a wasteful number, since it uses less digits than its factorization.

21399394 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 289220.

The product of its digits is 52488, while the sum is 40.

The square root of 21399394 is about 4625.9479028627. The cubic root of 21399394 is about 277.6304891808.

The spelling of 21399394 in words is "twenty-one million, three hundred ninety-nine thousand, three hundred ninety-four".