21091698 has 32 divisors (see below), whose sum is σ = 47229120. Its totient is φ = 6976800.

The previous prime is 21091663. The next prime is 21091703. The reversal of 21091698 is 89619012.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5973 + ... + 8823.

It is an arithmetic number, because the mean of its divisors is an integer number (1475910).

Almost surely, 2^21091698 is an apocalyptic number.

21091698 is an abundant number, since it is smaller than the sum of its proper divisors (26137422).

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

21091698 is a wasteful number, since it uses less digits than its factorization.

21091698 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2999 (or 2993 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 36.

The square root of 21091698 is about 4592.5698688207. The cubic root of 21091698 is about 276.2934025429.

The spelling of 21091698 in words is "twenty-one million, ninety-one thousand, six hundred ninety-eight".