21686771548 has 72 divisors (see below), whose sum is σ = 43678854800. Its totient is φ = 9419394816.

The previous prime is 21686771543. The next prime is 21686771549. The reversal of 21686771548 is 84517768612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21686771543) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2535463 + ... + 2544001.

Almost surely, 2^21686771548 is an apocalyptic number.

It is an amenable number.

21686771548 is an abundant number, since it is smaller than the sum of its proper divisors (21992083252).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21686771548 is a wasteful number, since it uses less digits than its factorization.

21686771548 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8616 (or 8571 counting only the distinct ones).

The product of its digits is 4515840, while the sum is 55.

The spelling of 21686771548 in words is "twenty-one billion, six hundred eighty-six million, seven hundred seventy-one thousand, five hundred forty-eight".