21921386 has 4 divisors (see below), whose sum is σ = 32882082. Its totient is φ = 10960692.

The previous prime is 21921377. The next prime is 21921397. The reversal of 21921386 is 68312912.

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., 17901361 + 4020025 = 4231^2 + 2005^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5480345 + ... + 5480348.

Almost surely, 2^21921386 is an apocalyptic number.

21921386 is a deficient number, since it is larger than the sum of its proper divisors (10960696).

21921386 is a wasteful number, since it uses less digits than its factorization.

21921386 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10960695.

The product of its digits is 5184, while the sum is 32.

The square root of 21921386 is about 4682.0279794123. The cubic root of 21921386 is about 279.8697778812.

The spelling of 21921386 in words is "twenty-one million, nine hundred twenty-one thousand, three hundred eighty-six".