645388031 has 2 divisors, whose sum is σ = 645388032. Its totient is φ = 645388030.

The previous prime is 645387971. The next prime is 645388097. The reversal of 645388031 is 130883546.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 645388031 - 2¹⁰ = 645387007 is a prime.

It is a super-2 number, since 2×645388031² = 833051421116113922, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645388531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322694015 + 322694016.

It is an arithmetic number, because the mean of its divisors is an integer number (322694016).

Almost surely, 2^645388031 is an apocalyptic number.

645388031 is a deficient number, since it is larger than the sum of its proper divisors (1).

645388031 is an equidigital number, since it uses as much as digits as its factorization.

645388031 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 69120, while the sum is 38.

The square root of 645388031 is about 25404.4884026426. The cubic root of 645388031 is about 864.1854878499.

The spelling of 645388031 in words is "six hundred forty-five million, three hundred eighty-eight thousand, thirty-one".