261652217621 has 2 divisors, whose sum is σ = 261652217622. Its totient is φ = 261652217620.

The previous prime is 261652217611. The next prime is 261652217633. The reversal of 261652217621 is 126712256162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 200390522500 + 61261695121 = 447650^2 + 247511^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261652217621 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261652217611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130826108810 + 130826108811.

It is an arithmetic number, because the mean of its divisors is an integer number (130826108811).

Almost surely, 2^261652217621 is an apocalyptic number.

It is an amenable number.

261652217621 is a deficient number, since it is larger than the sum of its proper divisors (1).

261652217621 is an equidigital number, since it uses as much as digits as its factorization.

261652217621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 120960, while the sum is 41.

The spelling of 261652217621 in words is "two hundred sixty-one billion, six hundred fifty-two million, two hundred seventeen thousand, six hundred twenty-one".