661554263 has 2 divisors, whose sum is σ = 661554264. Its totient is φ = 661554262.

The previous prime is 661554247. The next prime is 661554277. The reversal of 661554263 is 362455166.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 661554263 - 2⁴ = 661554247 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661554233) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330777131 + 330777132.

It is an arithmetic number, because the mean of its divisors is an integer number (330777132).

Almost surely, 2^661554263 is an apocalyptic number.

661554263 is a deficient number, since it is larger than the sum of its proper divisors (1).

661554263 is an equidigital number, since it uses as much as digits as its factorization.

661554263 is an evil number, because the sum of its binary digits is even.

The product of its digits is 129600, while the sum is 38.

The square root of 661554263 is about 25720.6971717331. The cubic root of 661554263 is about 871.3416841859.

The spelling of 661554263 in words is "six hundred sixty-one million, five hundred fifty-four thousand, two hundred sixty-three".