661564661119 has 4 divisors (see below), whose sum is σ = 661566345480. Its totient is φ = 661562976760.

The previous prime is 661564661113. The next prime is 661564661123. The reversal of 661564661119 is 911166465166.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 911166465166 = 2 ⋅455583232583.

It is a cyclic number.

It is not a de Polignac number, because 661564661119 - 2²⁷ = 661430443391 is a prime.

It is a super-2 number, since 2×661564661119² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661564661113) 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, 93477 + ... + 1154065.

It is an arithmetic number, because the mean of its divisors is an integer number (165391586370).

Almost surely, 2^661564661119 is an apocalyptic number.

661564661119 is a deficient number, since it is larger than the sum of its proper divisors (1684361).

661564661119 is a wasteful number, since it uses less digits than its factorization.

661564661119 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1684360.

The product of its digits is 1399680, while the sum is 52.

The spelling of 661564661119 in words is "six hundred sixty-one billion, five hundred sixty-four million, six hundred sixty-one thousand, one hundred nineteen".