661917070691 has 4 divisors (see below), whose sum is σ = 662061252384. Its totient is φ = 661772889000.

The previous prime is 661917070687. The next prime is 661917070723. The reversal of 661917070691 is 196070719166.

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 661917070691 - 2² = 661917070687 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661917070651) 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, 72083960 + ... + 72093141.

It is an arithmetic number, because the mean of its divisors is an integer number (165515313096).

Almost surely, 2^661917070691 is an apocalyptic number.

661917070691 is a deficient number, since it is larger than the sum of its proper divisors (144181693).

661917070691 is a wasteful number, since it uses less digits than its factorization.

661917070691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 144181692.

The product of its (nonzero) digits is 857304, while the sum is 53.

The spelling of 661917070691 in words is "six hundred sixty-one billion, nine hundred seventeen million, seventy thousand, six hundred ninety-one".