20233111991 has 2 divisors, whose sum is σ = 20233111992. Its totient is φ = 20233111990.

The previous prime is 20233111979. The next prime is 20233112033. The reversal of 20233111991 is 19911133202.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20233111991 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20230111991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10116555995 + 10116555996.

It is an arithmetic number, because the mean of its divisors is an integer number (10116555996).

Almost surely, 2^20233111991 is an apocalyptic number.

20233111991 is a deficient number, since it is larger than the sum of its proper divisors (1).

20233111991 is an equidigital number, since it uses as much as digits as its factorization.

20233111991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2916, while the sum is 32.

The spelling of 20233111991 in words is "twenty billion, two hundred thirty-three million, one hundred eleven thousand, nine hundred ninety-one".