20697944591 has 2 divisors, whose sum is σ = 20697944592. Its totient is φ = 20697944590.

The previous prime is 20697944549. The next prime is 20697944609. The reversal of 20697944591 is 19544979602.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20697944591 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20697944791) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10348972295 + 10348972296.

It is an arithmetic number, because the mean of its divisors is an integer number (10348972296).

Almost surely, 2^20697944591 is an apocalyptic number.

20697944591 is a deficient number, since it is larger than the sum of its proper divisors (1).

20697944591 is an equidigital number, since it uses as much as digits as its factorization.

20697944591 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4898880, while the sum is 56.

The spelling of 20697944591 in words is "twenty billion, six hundred ninety-seven million, nine hundred forty-four thousand, five hundred ninety-one".