18780377661 has 16 divisors (see below), whose sum is σ = 27838832320. Its totient is φ = 12513029040.

The previous prime is 18780377653. The next prime is 18780377663. The reversal of 18780377661 is 16677308781.

It is not a de Polignac number, because 18780377661 - 2³ = 18780377653 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 18780377598 and 18780377607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18780377663) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 152755 + ... + 246768.

It is an arithmetic number, because the mean of its divisors is an integer number (1739927020).

Almost surely, 2^18780377661 is an apocalyptic number.

It is an amenable number.

18780377661 is a deficient number, since it is larger than the sum of its proper divisors (9058454659).

18780377661 is a wasteful number, since it uses less digits than its factorization.

18780377661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 401273 (or 401267 counting only the distinct ones).

The product of its (nonzero) digits is 2370816, while the sum is 54.

The spelling of 18780377661 in words is "eighteen billion, seven hundred eighty million, three hundred seventy-seven thousand, six hundred sixty-one".