21920986 has 4 divisors (see below), whose sum is σ = 32881482. Its totient is φ = 10960492.

The previous prime is 21920963. The next prime is 21920989. The reversal of 21920986 is 68902912.

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

It can be written as a sum of positive squares in only one way, i.e., 18966025 + 2954961 = 4355^2 + 1719^2 .

It is not an unprimeable number, because it can be changed into a prime (21920989) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5480245 + ... + 5480248.

Almost surely, 2^21920986 is an apocalyptic number.

21920986 is a deficient number, since it is larger than the sum of its proper divisors (10960496).

21920986 is a wasteful number, since it uses less digits than its factorization.

21920986 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10960495.

The product of its (nonzero) digits is 15552, while the sum is 37.

The square root of 21920986 is about 4681.9852626851. The cubic root of 21920986 is about 279.8680756076.

The spelling of 21920986 in words is "twenty-one million, nine hundred twenty thousand, nine hundred eighty-six".