21399634 has 8 divisors (see below), whose sum is σ = 33987708. Its totient is φ = 10070400.

The previous prime is 21399563. The next prime is 21399649. The reversal of 21399634 is 43699312.

It can be written as a sum of positive squares in 2 ways, for example, as 19140625 + 2259009 = 4375^2 + 1503^2 .

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

It is a junction number, because it is equal to n+sod(n) for n = 21399593 and 21399602.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 314667 + ... + 314734.

Almost surely, 2^21399634 is an apocalyptic number.

21399634 is a deficient number, since it is larger than the sum of its proper divisors (12588074).

21399634 is a wasteful number, since it uses less digits than its factorization.

21399634 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 629420.

The product of its digits is 34992, while the sum is 37.

The square root of 21399634 is about 4625.9738434194. The cubic root of 21399634 is about 277.6315270773.

The spelling of 21399634 in words is "twenty-one million, three hundred ninety-nine thousand, six hundred thirty-four".