21778867156 has 24 divisors (see below), whose sum is σ = 38186805440. Its totient is φ = 10868375232.

The previous prime is 21778867153. The next prime is 21778867157. The reversal of 21778867156 is 65176887712.

It is a self number, because there is not a number n which added to its sum of digits gives 21778867156.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21778867153) 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, 6681055 + ... + 6684313.

Almost surely, 2^21778867156 is an apocalyptic number.

It is an amenable number.

21778867156 is a deficient number, since it is larger than the sum of its proper divisors (16407938284).

21778867156 is a wasteful number, since it uses less digits than its factorization.

21778867156 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5983 (or 5981 counting only the distinct ones).

The product of its digits is 7902720, while the sum is 58.

The spelling of 21778867156 in words is "twenty-one billion, seven hundred seventy-eight million, eight hundred sixty-seven thousand, one hundred fifty-six".