172397021 has 2 divisors, whose sum is σ = 172397022. Its totient is φ = 172397020.

The previous prime is 172396993. The next prime is 172397053. The reversal of 172397021 is 120793271.

172397021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an a-pointer prime, because the next prime (172397053) can be obtained adding 172397021 to its sum of digits (32).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 172396900 + 121 = 13130^2 + 11^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-172397021 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (172397521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 86198510 + 86198511.

It is an arithmetic number, because the mean of its divisors is an integer number (86198511).

Almost surely, 2^172397021 is an apocalyptic number.

It is an amenable number.

172397021 is a deficient number, since it is larger than the sum of its proper divisors (1).

172397021 is an equidigital number, since it uses as much as digits as its factorization.

172397021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5292, while the sum is 32.

The square root of 172397021 is about 13130.0046077677. The cubic root of 172397021 is about 556.5573455149.

The spelling of 172397021 in words is "one hundred seventy-two million, three hundred ninety-seven thousand, twenty-one".