661666047 has 32 divisors (see below), whose sum is σ = 1074511872. Its totient is φ = 353949024.

The previous prime is 661666043. The next prime is 661666073. The reversal of 661666047 is 740666166.

It is not a de Polignac number, because 661666047 - 2² = 661666043 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661666043) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 8128 + ... + 37274.

It is an arithmetic number, because the mean of its divisors is an integer number (33578496).

Almost surely, 2^661666047 is an apocalyptic number.

661666047 is a deficient number, since it is larger than the sum of its proper divisors (412845825).

661666047 is a wasteful number, since it uses less digits than its factorization.

661666047 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29227.

The product of its (nonzero) digits is 217728, while the sum is 42.

The square root of 661666047 is about 25722.8701159105. The cubic root of 661666047 is about 871.3907588064.

The spelling of 661666047 in words is "six hundred sixty-one million, six hundred sixty-six thousand, forty-seven".