20155661666 has 32 divisors (see below), whose sum is σ = 35515238400. Its totient is φ = 8575048608.

The previous prime is 20155661641. The next prime is 20155661671. The reversal of 20155661666 is 66616655102.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13250 + ... + 201213.

It is an arithmetic number, because the mean of its divisors is an integer number (1109851200).

Almost surely, 2^20155661666 is an apocalyptic number.

20155661666 is a deficient number, since it is larger than the sum of its proper divisors (15359576734).

20155661666 is a wasteful number, since it uses less digits than its factorization.

20155661666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 214623 (or 214609 counting only the distinct ones).

The product of its (nonzero) digits is 388800, while the sum is 44.

The spelling of 20155661666 in words is "twenty billion, one hundred fifty-five million, six hundred sixty-one thousand, six hundred sixty-six".