661666051 has 8 divisors (see below), whose sum is σ = 696729600. Its totient is φ = 626626440.

The previous prime is 661666043. The next prime is 661666073. The reversal of 661666051 is 150666166.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 661666051 - 2³ = 661666043 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 661666051.

It is not an unprimeable number, because it can be changed into a prime (661666091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 92286 + ... + 99196.

It is an arithmetic number, because the mean of its divisors is an integer number (87091200).

Almost surely, 2^661666051 is an apocalyptic number.

661666051 is a deficient number, since it is larger than the sum of its proper divisors (35063549).

661666051 is a wasteful number, since it uses less digits than its factorization.

661666051 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11969.

The product of its (nonzero) digits is 38880, while the sum is 37.

The square root of 661666051 is about 25722.8701936623. The cubic root of 661666051 is about 871.3907605624.

The spelling of 661666051 in words is "six hundred sixty-one million, six hundred sixty-six thousand, fifty-one".