21918490 has 32 divisors (see below), whose sum is σ = 44530560. Its totient is φ = 7694400.

The previous prime is 21918473. The next prime is 21918509. The reversal of 21918490 is 9481912.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 246 + ... + 6625.

It is an arithmetic number, because the mean of its divisors is an integer number (1391580).

Almost surely, 2^21918490 is an apocalyptic number.

21918490 is an abundant number, since it is smaller than the sum of its proper divisors (22612070).

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

21918490 is a wasteful number, since it uses less digits than its factorization.

21918490 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6918.

The product of its (nonzero) digits is 5184, while the sum is 34.

The square root of 21918490 is about 4681.7187015027. The cubic root of 21918490 is about 279.8574529523.

The spelling of 21918490 in words is "twenty-one million, nine hundred eighteen thousand, four hundred ninety".