21673156560 has 160 divisors (see below), whose sum is σ = 73346055552. Its totient is φ = 5250416640.

The previous prime is 21673156529. The next prime is 21673156567. The reversal of 21673156560 is 6565137612.

It is a hoax number, since the sum of its digits (42) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21673156567) by changing a digit.

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 31 ways as a sum of consecutive naturals, for example, 6907312 + ... + 6910448.

Almost surely, 2^21673156560 is an apocalyptic number.

21673156560 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21673156560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36673027776).

21673156560 is an abundant number, since it is smaller than the sum of its proper divisors (51672898992).

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

21673156560 is a wasteful number, since it uses less digits than its factorization.

21673156560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5781 (or 5775 counting only the distinct ones).

The product of its (nonzero) digits is 226800, while the sum is 42.

The spelling of 21673156560 in words is "twenty-one billion, six hundred seventy-three million, one hundred fifty-six thousand, five hundred sixty".