172781491 has 2 divisors, whose sum is σ = 172781492. Its totient is φ = 172781490.

The previous prime is 172781471. The next prime is 172781519. The reversal of 172781491 is 194187271.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 172781491 - 2¹⁹ = 172257203 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (172781461) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 86390745 + 86390746.

It is an arithmetic number, because the mean of its divisors is an integer number (86390746).

Almost surely, 2^172781491 is an apocalyptic number.

172781491 is a deficient number, since it is larger than the sum of its proper divisors (1).

172781491 is an equidigital number, since it uses as much as digits as its factorization.

172781491 is an evil number, because the sum of its binary digits is even.

The product of its digits is 28224, while the sum is 40.

The square root of 172781491 is about 13144.6373476030. The cubic root of 172781491 is about 556.9707724791.

It can be divided in two parts, 17278 and 1491, that added together give a square (18769 = 137²).

The spelling of 172781491 in words is "one hundred seventy-two million, seven hundred eighty-one thousand, four hundred ninety-one".