19501660691 has 2 divisors, whose sum is σ = 19501660692. Its totient is φ = 19501660690.

The previous prime is 19501660679. The next prime is 19501660729. The reversal of 19501660691 is 19606610591.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19501660691 is a prime.

It is not a weakly prime, because it can be changed into another prime (19501660621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9750830345 + 9750830346.

It is an arithmetic number, because the mean of its divisors is an integer number (9750830346).

Almost surely, 2^19501660691 is an apocalyptic number.

19501660691 is a deficient number, since it is larger than the sum of its proper divisors (1).

19501660691 is an equidigital number, since it uses as much as digits as its factorization.

19501660691 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 87480, while the sum is 44.

The spelling of 19501660691 in words is "nineteen billion, five hundred one million, six hundred sixty thousand, six hundred ninety-one".