21091606289 has 4 divisors (see below), whose sum is σ = 22714037556. Its totient is φ = 19469175024.

The previous prime is 21091606259. The next prime is 21091606309. The reversal of 21091606289 is 98260619012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6361657600 + 14729948689 = 79760^2 + 121367^2 .

It is not a de Polignac number, because 21091606289 - 2²⁰ = 21090557713 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21091606219) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 811215614 + ... + 811215639.

It is an arithmetic number, because the mean of its divisors is an integer number (5678509389).

Almost surely, 2^21091606289 is an apocalyptic number.

It is an amenable number.

21091606289 is a deficient number, since it is larger than the sum of its proper divisors (1622431267).

21091606289 is a wasteful number, since it uses less digits than its factorization.

21091606289 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1622431266.

The product of its (nonzero) digits is 93312, while the sum is 44.

The spelling of 21091606289 in words is "twenty-one billion, ninety-one million, six hundred six thousand, two hundred eighty-nine".