1661255623249 has 2 divisors, whose sum is σ = 1661255623250. Its totient is φ = 1661255623248.

The previous prime is 1661255623241. The next prime is 1661255623259. The reversal of 1661255623249 is 9423265521661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1428359619600 + 232896003649 = 1195140^2 + 482593^2 .

It is a cyclic number.

It is not a de Polignac number, because 1661255623249 - 2³ = 1661255623241 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1661255623196 and 1661255623205.

It is not a weakly prime, because it can be changed into another prime (1661255623241) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 830627811624 + 830627811625.

It is an arithmetic number, because the mean of its divisors is an integer number (830627811625).

Almost surely, 2^{1661255623249} is an apocalyptic number.

It is an amenable number.

1661255623249 is a deficient number, since it is larger than the sum of its proper divisors (1).

1661255623249 is an equidigital number, since it uses as much as digits as its factorization.

1661255623249 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4665600, while the sum is 52.

The spelling of 1661255623249 in words is "one trillion, six hundred sixty-one billion, two hundred fifty-five million, six hundred twenty-three thousand, two hundred forty-nine".