21986232691 has 4 divisors (see below), whose sum is σ = 22497540472. Its totient is φ = 21474924912.

The previous prime is 21986232677. The next prime is 21986232731. The reversal of 21986232691 is 19623268912.

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 21986232691 - 2⁵ = 21986232659 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21986232661) 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, 255653826 + ... + 255653911.

It is an arithmetic number, because the mean of its divisors is an integer number (5624385118).

Almost surely, 2^21986232691 is an apocalyptic number.

21986232691 is a deficient number, since it is larger than the sum of its proper divisors (511307781).

21986232691 is an equidigital number, since it uses as much as digits as its factorization.

21986232691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 511307780.

The product of its digits is 559872, while the sum is 49.

The spelling of 21986232691 in words is "twenty-one billion, nine hundred eighty-six million, two hundred thirty-two thousand, six hundred ninety-one".