21207149291 has 4 divisors (see below), whose sum is σ = 21207485472. Its totient is φ = 21206813112.

The previous prime is 21207149279. The next prime is 21207149323. The reversal of 21207149291 is 19294170212.

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

It is a cyclic number.

It is not a de Polignac number, because 21207149291 - 2¹⁸ = 21206887147 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21207143291) 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, 41876 + ... + 210161.

It is an arithmetic number, because the mean of its divisors is an integer number (5301871368).

Almost surely, 2^21207149291 is an apocalyptic number.

21207149291 is a deficient number, since it is larger than the sum of its proper divisors (336181).

21207149291 is an equidigital number, since it uses as much as digits as its factorization.

21207149291 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 336180.

The product of its (nonzero) digits is 18144, while the sum is 38.

The spelling of 21207149291 in words is "twenty-one billion, two hundred seven million, one hundred forty-nine thousand, two hundred ninety-one".