21099390 has 32 divisors (see below), whose sum is σ = 54534816. Its totient is φ = 5193600.

The previous prime is 21099383. The next prime is 21099391. The reversal of 21099390 is 9399012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21099391) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 26661 + ... + 27440.

It is an arithmetic number, because the mean of its divisors is an integer number (1704213).

Almost surely, 2^21099390 is an apocalyptic number.

21099390 is an abundant number, since it is smaller than the sum of its proper divisors (33435426).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21099390 is a wasteful number, since it uses less digits than its factorization.

21099390 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54124.

The product of its (nonzero) digits is 4374, while the sum is 33.

The square root of 21099390 is about 4593.4072321100. The cubic root of 21099390 is about 276.3269859075.

The spelling of 21099390 in words is "twenty-one million, ninety-nine thousand, three hundred ninety".