21798646 has 4 divisors (see below), whose sum is σ = 32697972. Its totient is φ = 10899322.

The previous prime is 21798631. The next prime is 21798653. The reversal of 21798646 is 64689712.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5449660 + ... + 5449663.

It is an arithmetic number, because the mean of its divisors is an integer number (8174493).

Almost surely, 2^21798646 is an apocalyptic number.

21798646 is a deficient number, since it is larger than the sum of its proper divisors (10899326).

21798646 is a wasteful number, since it uses less digits than its factorization.

21798646 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10899325.

The product of its digits is 145152, while the sum is 43.

The square root of 21798646 is about 4668.9020122508. The cubic root of 21798646 is about 279.3464604739.

The spelling of 21798646 in words is "twenty-one million, seven hundred ninety-eight thousand, six hundred forty-six".