661427661 has 4 divisors (see below), whose sum is σ = 881903552. Its totient is φ = 440951772.

The previous prime is 661427659. The next prime is 661427719. The reversal of 661427661 is 166724166.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 661427661 - 2¹ = 661427659 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 (661427561) 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, 110237941 + ... + 110237946.

It is an arithmetic number, because the mean of its divisors is an integer number (220475888).

Almost surely, 2^661427661 is an apocalyptic number.

It is an amenable number.

661427661 is a deficient number, since it is larger than the sum of its proper divisors (220475891).

661427661 is a wasteful number, since it uses less digits than its factorization.

661427661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 220475890.

The product of its digits is 72576, while the sum is 39.

The square root of 661427661 is about 25718.2359620562. The cubic root of 661427661 is about 871.2860975955.

The spelling of 661427661 in words is "six hundred sixty-one million, four hundred twenty-seven thousand, six hundred sixty-one".