20991291226 has 8 divisors (see below), whose sum is σ = 31580370900. Its totient is φ = 10464500928.

The previous prime is 20991291221. The next prime is 20991291253. The reversal of 20991291226 is 62219219902.

It can be written as a sum of positive squares in 2 ways, for example, as 20841253225 + 150038001 = 144365^2 + 12249^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (20991291221) 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, 15571501 + ... + 15572848.

Almost surely, 2^20991291226 is an apocalyptic number.

20991291226 is a deficient number, since it is larger than the sum of its proper divisors (10589079674).

20991291226 is a wasteful number, since it uses less digits than its factorization.

20991291226 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31144688.

The product of its (nonzero) digits is 69984, while the sum is 43.

The spelling of 20991291226 in words is "twenty billion, nine hundred ninety-one million, two hundred ninety-one thousand, two hundred twenty-six".