261364643 has 2 divisors, whose sum is σ = 261364644. Its totient is φ = 261364642.

The previous prime is 261364639. The next prime is 261364661. The reversal of 261364643 is 346463162.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 261364643 - 2² = 261364639 is a prime.

It is a super-2 number, since 2×261364643² = 136622953221034898, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (261364673) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130682321 + 130682322.

It is an arithmetic number, because the mean of its divisors is an integer number (130682322).

Almost surely, 2^261364643 is an apocalyptic number.

261364643 is a deficient number, since it is larger than the sum of its proper divisors (1).

261364643 is an equidigital number, since it uses as much as digits as its factorization.

261364643 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 62208, while the sum is 35.

The square root of 261364643 is about 16166.7758999746. The cubic root of 261364643 is about 639.3651280730.

The spelling of 261364643 in words is "two hundred sixty-one million, three hundred sixty-four thousand, six hundred forty-three".