21891944258 has 6 divisors (see below), whose sum is σ = 32838230259. Its totient is φ = 10945867506.

The previous prime is 21891944233. The next prime is 21891944273. The reversal of 21891944258 is 85244919812.

It can be written as a sum of positive squares in only one way, i.e., 10945972129 + 10945972129 = 104623^2 + 104623^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=104623.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 156935 + ... + 261557.

Almost surely, 2^21891944258 is an apocalyptic number.

21891944258 is a deficient number, since it is larger than the sum of its proper divisors (10946286001).

21891944258 is an frugal number, since it uses more digits than its factorization.

21891944258 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 209248 (or 104625 counting only the distinct ones).

The product of its digits is 1658880, while the sum is 53.

The spelling of 21891944258 in words is "twenty-one billion, eight hundred ninety-one million, nine hundred forty-four thousand, two hundred fifty-eight".