261181250621 has 2 divisors, whose sum is σ = 261181250622. Its totient is φ = 261181250620.

The previous prime is 261181250599. The next prime is 261181250633. The reversal of 261181250621 is 126052181162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 149835571396 + 111345679225 = 387086^2 + 333685^2 .

It is a cyclic number.

It is not a de Polignac number, because 261181250621 - 2²² = 261177056317 is a prime.

It is a super-2 number, since 2×261181250621² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261181250021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130590625310 + 130590625311.

It is an arithmetic number, because the mean of its divisors is an integer number (130590625311).

Almost surely, 2^261181250621 is an apocalyptic number.

It is an amenable number.

261181250621 is a deficient number, since it is larger than the sum of its proper divisors (1).

261181250621 is an equidigital number, since it uses as much as digits as its factorization.

261181250621 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 11520, while the sum is 35.

The spelling of 261181250621 in words is "two hundred sixty-one billion, one hundred eighty-one million, two hundred fifty thousand, six hundred twenty-one".