21256737368 has 8 divisors (see below), whose sum is σ = 39856382580. Its totient is φ = 10628368680.

The previous prime is 21256737361. The next prime is 21256737371. The reversal of 21256737368 is 86373765212.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21256737361) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1328546078 + ... + 1328546093.

Almost surely, 2^21256737368 is an apocalyptic number.

It is an amenable number.

21256737368 is a deficient number, since it is larger than the sum of its proper divisors (18599645212).

21256737368 is a wasteful number, since it uses less digits than its factorization.

21256737368 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2657092177 (or 2657092173 counting only the distinct ones).

The product of its digits is 2540160, while the sum is 50.

The spelling of 21256737368 in words is "twenty-one billion, two hundred fifty-six million, seven hundred thirty-seven thousand, three hundred sixty-eight".