21009808254 has 16 divisors (see below), whose sum is σ = 42113206800. Its totient is φ = 6987671040.

The previous prime is 21009808249. The next prime is 21009808273. The reversal of 21009808254 is 45280890012.

It is a congruent 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, 3896677 + ... + 3902064.

It is an arithmetic number, because the mean of its divisors is an integer number (2632075425).

Almost surely, 2^21009808254 is an apocalyptic number.

21009808254 is an abundant number, since it is smaller than the sum of its proper divisors (21103398546).

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

21009808254 is a wasteful number, since it uses less digits than its factorization.

21009808254 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7799195.

The product of its (nonzero) digits is 46080, while the sum is 39.

The spelling of 21009808254 in words is "twenty-one billion, nine million, eight hundred eight thousand, two hundred fifty-four".