21572308173 has 16 divisors (see below), whose sum is σ = 30989294336. Its totient is φ = 13269407040.

The previous prime is 21572308159. The next prime is 21572308193. The reversal of 21572308173 is 37180327512.

It is not a de Polignac number, because 21572308173 - 2⁴ = 21572308157 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21572308133) 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, 31738 + ... + 210123.

It is an arithmetic number, because the mean of its divisors is an integer number (1936830896).

Almost surely, 2^21572308173 is an apocalyptic number.

It is an amenable number.

21572308173 is a deficient number, since it is larger than the sum of its proper divisors (9416986163).

21572308173 is a wasteful number, since it uses less digits than its factorization.

21572308173 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 244164.

The product of its (nonzero) digits is 70560, while the sum is 39.

The spelling of 21572308173 in words is "twenty-one billion, five hundred seventy-two million, three hundred eight thousand, one hundred seventy-three".