661185275407 has 4 divisors (see below), whose sum is σ = 663147249856. Its totient is φ = 659223300960.

The previous prime is 661185275389. The next prime is 661185275411. The reversal of 661185275407 is 704572581166.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-661185275407 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661185285407) 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, 980986719 + ... + 980987392.

It is an arithmetic number, because the mean of its divisors is an integer number (165786812464).

Almost surely, 2^661185275407 is an apocalyptic number.

661185275407 is a deficient number, since it is larger than the sum of its proper divisors (1961974449).

661185275407 is a wasteful number, since it uses less digits than its factorization.

661185275407 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1961974448.

The product of its (nonzero) digits is 2822400, while the sum is 52.

The spelling of 661185275407 in words is "six hundred sixty-one billion, one hundred eighty-five million, two hundred seventy-five thousand, four hundred seven".