645531169 has 2 divisors, whose sum is σ = 645531170. Its totient is φ = 645531168.

The previous prime is 645531127. The next prime is 645531181. The reversal of 645531169 is 961135546.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 359481600 + 286049569 = 18960^2 + 16913^2 .

It is a cyclic number.

It is not a de Polignac number, because 645531169 - 2¹⁷ = 645400097 is a prime.

It is a super-2 number, since 2×645531169² = 833420980301013122, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (645591169) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322765584 + 322765585.

It is an arithmetic number, because the mean of its divisors is an integer number (322765585).

Almost surely, 2^645531169 is an apocalyptic number.

It is an amenable number.

645531169 is a deficient number, since it is larger than the sum of its proper divisors (1).

645531169 is an equidigital number, since it uses as much as digits as its factorization.

645531169 is an evil number, because the sum of its binary digits is even.

The product of its digits is 97200, while the sum is 40.

The square root of 645531169 is about 25407.3054258022. The cubic root of 645531169 is about 864.2493711948.

The spelling of 645531169 in words is "six hundred forty-five million, five hundred thirty-one thousand, one hundred sixty-nine".