21090858 has 16 divisors (see below), whose sum is σ = 42334176. Its totient is φ = 7004880.

The previous prime is 21090841. The next prime is 21090871. The reversal of 21090858 is 85809012.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4513 + ... + 7908.

It is an arithmetic number, because the mean of its divisors is an integer number (2645886).

Almost surely, 2^21090858 is an apocalyptic number.

21090858 is an abundant number, since it is smaller than the sum of its proper divisors (21243318).

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

21090858 is a wasteful number, since it uses less digits than its factorization.

21090858 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12709.

The product of its (nonzero) digits is 5760, while the sum is 33.

The square root of 21090858 is about 4592.4784158448. The cubic root of 21090858 is about 276.2897345983.

The spelling of 21090858 in words is "twenty-one million, ninety thousand, eight hundred fifty-eight".