661942739 has 4 divisors (see below), whose sum is σ = 662260200. Its totient is φ = 661625280.

The previous prime is 661942711. The next prime is 661942741. The reversal of 661942739 is 937249166.

It is a happy number.

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 661942739 - 2²⁰ = 660894163 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 661942693 and 661942702.

It is not an unprimeable number, because it can be changed into a prime (661942709) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 155582 + ... + 159779.

It is an arithmetic number, because the mean of its divisors is an integer number (165565050).

Almost surely, 2^661942739 is an apocalyptic number.

661942739 is a deficient number, since it is larger than the sum of its proper divisors (317461).

661942739 is a wasteful number, since it uses less digits than its factorization.

661942739 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 317460.

The product of its digits is 489888, while the sum is 47.

The square root of 661942739 is about 25728.2478804912. The cubic root of 661942739 is about 871.5122064020.

The spelling of 661942739 in words is "six hundred sixty-one million, nine hundred forty-two thousand, seven hundred thirty-nine".