1663577261 has 2 divisors, whose sum is σ = 1663577262. Its totient is φ = 1663577260.

The previous prime is 1663577233. The next prime is 1663577263. The reversal of 1663577261 is 1627753661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 907877161 + 755700100 = 30131^2 + 27490^2 .

It is a cyclic number.

It is not a de Polignac number, because 1663577261 - 2¹⁸ = 1663315117 is a prime.

Together with 1663577263, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1663577263) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 831788630 + 831788631.

It is an arithmetic number, because the mean of its divisors is an integer number (831788631).

Almost surely, 2^1663577261 is an apocalyptic number.

It is an amenable number.

1663577261 is a deficient number, since it is larger than the sum of its proper divisors (1).

1663577261 is an equidigital number, since it uses as much as digits as its factorization.

1663577261 is an evil number, because the sum of its binary digits is even.

The product of its digits is 317520, while the sum is 44.

The square root of 1663577261 is about 40786.9741584246. The cubic root of 1663577261 is about 1184.8980692945.

The spelling of 1663577261 in words is "one billion, six hundred sixty-three million, five hundred seventy-seven thousand, two hundred sixty-one".