21320112991 has 2 divisors, whose sum is σ = 21320112992. Its totient is φ = 21320112990.

The previous prime is 21320112943. The next prime is 21320113021. The reversal of 21320112991 is 19921102312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21320112991 - 2⁹ = 21320112479 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21320112901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10660056495 + 10660056496.

It is an arithmetic number, because the mean of its divisors is an integer number (10660056496).

Almost surely, 2^21320112991 is an apocalyptic number.

21320112991 is a deficient number, since it is larger than the sum of its proper divisors (1).

21320112991 is an equidigital number, since it uses as much as digits as its factorization.

21320112991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1944, while the sum is 31.

The spelling of 21320112991 in words is "twenty-one billion, three hundred twenty million, one hundred twelve thousand, nine hundred ninety-one".