645067144721 has 2 divisors, whose sum is σ = 645067144722. Its totient is φ = 645067144720.

The previous prime is 645067144633. The next prime is 645067144723. The reversal of 645067144721 is 127441760546.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 344504433025 + 300562711696 = 586945^2 + 548236^2 .

It is a cyclic number.

It is not a de Polignac number, because 645067144721 - 2¹⁴ = 645067128337 is a prime.

It is a super-2 number, since 2×645067144721² (a number of 24 digits) contains 22 as substring.

It is a Sophie Germain prime.

Together with 645067144723, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (645067144723) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322533572360 + 322533572361.

It is an arithmetic number, because the mean of its divisors is an integer number (322533572361).

Almost surely, 2^645067144721 is an apocalyptic number.

It is an amenable number.

645067144721 is a deficient number, since it is larger than the sum of its proper divisors (1).

645067144721 is an equidigital number, since it uses as much as digits as its factorization.

645067144721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1128960, while the sum is 47.

The spelling of 645067144721 in words is "six hundred forty-five billion, sixty-seven million, one hundred forty-four thousand, seven hundred twenty-one".