21911390 has 16 divisors (see below), whose sum is σ = 39664080. Its totient is φ = 8714880.

The previous prime is 21911377. The next prime is 21911399. The reversal of 21911390 is 9311912.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21911399) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4331 + ... + 7910.

It is an arithmetic number, because the mean of its divisors is an integer number (2479005).

Almost surely, 2^21911390 is an apocalyptic number.

21911390 is a deficient number, since it is larger than the sum of its proper divisors (17752690).

21911390 is a wasteful number, since it uses less digits than its factorization.

21911390 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12427.

The product of its (nonzero) digits is 486, while the sum is 26.

The square root of 21911390 is about 4680.9603715477. The cubic root of 21911390 is about 279.8272318543.

The spelling of 21911390 in words is "twenty-one million, nine hundred eleven thousand, three hundred ninety".