21647978436 has 24 divisors (see below), whose sum is σ = 57727942720. Its totient is φ = 6185136672.

The previous prime is 21647978423. The next prime is 21647978533. The reversal of 21647978436 is 63487974612.

It is a super-3 number, since 3×21647978436³ (a number of 32 digits) contains 333 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 128856931 + ... + 128857098.

Almost surely, 2^21647978436 is an apocalyptic number.

It is an amenable number.

21647978436 is an abundant number, since it is smaller than the sum of its proper divisors (36079964284).

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

21647978436 is a wasteful number, since it uses less digits than its factorization.

21647978436 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 257714043 (or 257714041 counting only the distinct ones).

The product of its digits is 12192768, while the sum is 57.

The spelling of 21647978436 in words is "twenty-one billion, six hundred forty-seven million, nine hundred seventy-eight thousand, four hundred thirty-six".