661611607 has 4 divisors (see below), whose sum is σ = 661667400. Its totient is φ = 661555816.

The previous prime is 661611581. The next prime is 661611619. The reversal of 661611607 is 706116166.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-661611607 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 (661611647) 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, 2248 + ... + 36445.

It is an arithmetic number, because the mean of its divisors is an integer number (165416850).

Almost surely, 2^661611607 is an apocalyptic number.

661611607 is a deficient number, since it is larger than the sum of its proper divisors (55793).

661611607 is a wasteful number, since it uses less digits than its factorization.

661611607 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55792.

The product of its (nonzero) digits is 9072, while the sum is 34.

The square root of 661611607 is about 25721.8118918555. The cubic root of 661611607 is about 871.3668596334.

The spelling of 661611607 in words is "six hundred sixty-one million, six hundred eleven thousand, six hundred seven".