21780766198 has 16 divisors (see below), whose sum is σ = 32888340576. Its totient is φ = 10818226240.

The previous prime is 21780766193. The next prime is 21780766199. The reversal of 21780766198 is 89166708712.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21780766193) 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, 122490 + ... + 242002.

It is an arithmetic number, because the mean of its divisors is an integer number (2055521286).

Almost surely, 2^21780766198 is an apocalyptic number.

21780766198 is a deficient number, since it is larger than the sum of its proper divisors (11107574378).

21780766198 is a wasteful number, since it uses less digits than its factorization.

21780766198 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 120119.

The product of its (nonzero) digits is 2032128, while the sum is 55.

The spelling of 21780766198 in words is "twenty-one billion, seven hundred eighty million, seven hundred sixty-six thousand, one hundred ninety-eight".