661117783 has 2 divisors, whose sum is σ = 661117784. Its totient is φ = 661117782.

The previous prime is 661117747. The next prime is 661117799. The reversal of 661117783 is 387711166.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 661117783 - 2⁹ = 661117271 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661117883) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330558891 + 330558892.

It is an arithmetic number, because the mean of its divisors is an integer number (330558892).

Almost surely, 2^661117783 is an apocalyptic number.

661117783 is a deficient number, since it is larger than the sum of its proper divisors (1).

661117783 is an equidigital number, since it uses as much as digits as its factorization.

661117783 is an evil number, because the sum of its binary digits is even.

The product of its digits is 42336, while the sum is 40.

The square root of 661117783 is about 25712.2107762051. The cubic root of 661117783 is about 871.1500108728.

The spelling of 661117783 in words is "six hundred sixty-one million, one hundred seventeen thousand, seven hundred eighty-three".