661774493 has 2 divisors, whose sum is σ = 661774494. Its totient is φ = 661774492.

The previous prime is 661774471. The next prime is 661774499. The reversal of 661774493 is 394477166.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 485893849 + 175880644 = 22043^2 + 13262^2 .

It is a cyclic number.

It is not a de Polignac number, because 661774493 - 2²⁴ = 644997277 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661774499) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330887246 + 330887247.

It is an arithmetic number, because the mean of its divisors is an integer number (330887247).

Almost surely, 2^661774493 is an apocalyptic number.

It is an amenable number.

661774493 is a deficient number, since it is larger than the sum of its proper divisors (1).

661774493 is an equidigital number, since it uses as much as digits as its factorization.

661774493 is an evil number, because the sum of its binary digits is even.

The product of its digits is 762048, while the sum is 47.

The square root of 661774493 is about 25724.9779980470. The cubic root of 661774493 is about 871.4383627200.

The spelling of 661774493 in words is "six hundred sixty-one million, seven hundred seventy-four thousand, four hundred ninety-three".