21072178173 has 32 divisors (see below), whose sum is σ = 29928620032. Its totient is φ = 13164379200.

The previous prime is 21072178163. The next prime is 21072178177. The reversal of 21072178173 is 37187127012.

It is not a de Polignac number, because 21072178173 - 2¹² = 21072174077 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21072178177) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 711540 + ... + 740562.

It is an arithmetic number, because the mean of its divisors is an integer number (935269376).

Almost surely, 2^21072178173 is an apocalyptic number.

It is an amenable number.

21072178173 is a deficient number, since it is larger than the sum of its proper divisors (8856441859).

21072178173 is a wasteful number, since it uses less digits than its factorization.

21072178173 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29305.

The product of its (nonzero) digits is 32928, while the sum is 39.

The spelling of 21072178173 in words is "twenty-one billion, seventy-two million, one hundred seventy-eight thousand, one hundred seventy-three".