21397646 has 8 divisors (see below), whose sum is σ = 32396760. Its totient is φ = 10598728.

The previous prime is 21397633. The next prime is 21397669. The reversal of 21397646 is 64679312.

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

It is a congruent number.

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, 49781 + ... + 50208.

It is an arithmetic number, because the mean of its divisors is an integer number (4049595).

Almost surely, 2^21397646 is an apocalyptic number.

21397646 is a deficient number, since it is larger than the sum of its proper divisors (10999114).

21397646 is a wasteful number, since it uses less digits than its factorization.

21397646 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 100098.

The product of its digits is 54432, while the sum is 38.

The square root of 21397646 is about 4625.7589647538. The cubic root of 21397646 is about 277.6229296006.

The spelling of 21397646 in words is "twenty-one million, three hundred ninety-seven thousand, six hundred forty-six".