644060243 has 2 divisors, whose sum is σ = 644060244. Its totient is φ = 644060242.

The previous prime is 644060203. The next prime is 644060257. The reversal of 644060243 is 342060446.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644060243 is a prime.

It is a super-2 number, since 2×644060243² = 829627193226438098, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (644060203) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322030121 + 322030122.

It is an arithmetic number, because the mean of its divisors is an integer number (322030122).

Almost surely, 2^644060243 is an apocalyptic number.

644060243 is a deficient number, since it is larger than the sum of its proper divisors (1).

644060243 is an equidigital number, since it uses as much as digits as its factorization.

644060243 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 13824, while the sum is 29.

The square root of 644060243 is about 25378.3420065220. The cubic root of 644060243 is about 863.5924374311.

The spelling of 644060243 in words is "six hundred forty-four million, sixty thousand, two hundred forty-three".