645531685387 has 2 divisors, whose sum is σ = 645531685388. Its totient is φ = 645531685386.

The previous prime is 645531685289. The next prime is 645531685423. The reversal of 645531685387 is 783586135546.

645531685387 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 645531685387 - 2⁷ = 645531685259 is a prime.

It is a super-2 number, since 2×645531685387² (a number of 24 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (645531685187) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322765842693 + 322765842694.

It is an arithmetic number, because the mean of its divisors is an integer number (322765842694).

Almost surely, 2^645531685387 is an apocalyptic number.

645531685387 is a deficient number, since it is larger than the sum of its proper divisors (1).

645531685387 is an equidigital number, since it uses as much as digits as its factorization.

645531685387 is an evil number, because the sum of its binary digits is even.

The product of its digits is 72576000, while the sum is 61.

The spelling of 645531685387 in words is "six hundred forty-five billion, five hundred thirty-one million, six hundred eighty-five thousand, three hundred eighty-seven".