645168749 has 2 divisors, whose sum is σ = 645168750. Its totient is φ = 645168748.

The previous prime is 645168707. The next prime is 645168773. The reversal of 645168749 is 947861546.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 596238724 + 48930025 = 24418^2 + 6995^2 .

It is a cyclic number.

It is not a de Polignac number, because 645168749 - 2²⁸ = 376733293 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 645168697 and 645168706.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645168779) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322584374 + 322584375.

It is an arithmetic number, because the mean of its divisors is an integer number (322584375).

Almost surely, 2^645168749 is an apocalyptic number.

It is an amenable number.

645168749 is a deficient number, since it is larger than the sum of its proper divisors (1).

645168749 is an equidigital number, since it uses as much as digits as its factorization.

645168749 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1451520, while the sum is 50.

The square root of 645168749 is about 25400.1722238256. The cubic root of 645168749 is about 864.0876026608.

The spelling of 645168749 in words is "six hundred forty-five million, one hundred sixty-eight thousand, seven hundred forty-nine".