21647520673 has 16 divisors (see below), whose sum is σ = 23926098816. Its totient is φ = 19481271040.

The previous prime is 21647520637. The next prime is 21647520677. The reversal of 21647520673 is 37602574612.

It is a de Polignac number, because none of the positive numbers 2^k-21647520673 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21647520677) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1290963 + ... + 1307623.

It is an arithmetic number, because the mean of its divisors is an integer number (1495381176).

Almost surely, 2^21647520673 is an apocalyptic number.

21647520673 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

21647520673 is a deficient number, since it is larger than the sum of its proper divisors (2278578143).

21647520673 is a wasteful number, since it uses less digits than its factorization.

21647520673 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20024.

The product of its (nonzero) digits is 423360, while the sum is 43.

The spelling of 21647520673 in words is "twenty-one billion, six hundred forty-seven million, five hundred twenty thousand, six hundred seventy-three".