661420666 has 16 divisors (see below), whose sum is σ = 1105781760. Its totient is φ = 294874560.

The previous prime is 661420663. The next prime is 661420673. The reversal of 661420666 is 666024166.

It is not an unprimeable number, because it can be changed into a prime (661420663) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 511290 + ... + 512581.

It is an arithmetic number, because the mean of its divisors is an integer number (69111360).

Almost surely, 2^661420666 is an apocalyptic number.

661420666 is a deficient number, since it is larger than the sum of its proper divisors (444361094).

661420666 is a wasteful number, since it uses less digits than its factorization.

661420666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1023909.

The product of its (nonzero) digits is 62208, while the sum is 37.

The square root of 661420666 is about 25718.0999686991. The cubic root of 661420666 is about 871.2830261244.

The spelling of 661420666 in words is "six hundred sixty-one million, four hundred twenty thousand, six hundred sixty-six".