661456849 has 2 divisors, whose sum is σ = 661456850. Its totient is φ = 661456848.

The previous prime is 661456781. The next prime is 661456867. The reversal of 661456849 is 948654166.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 391446225 + 270010624 = 19785^2 + 16432^2 .

It is a cyclic number.

It is not a de Polignac number, because 661456849 - 2¹³ = 661448657 is a prime.

It is not a weakly prime, because it can be changed into another prime (661456879) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330728424 + 330728425.

It is an arithmetic number, because the mean of its divisors is an integer number (330728425).

Almost surely, 2^661456849 is an apocalyptic number.

It is an amenable number.

661456849 is a deficient number, since it is larger than the sum of its proper divisors (1).

661456849 is an equidigital number, since it uses as much as digits as its factorization.

661456849 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1244160, while the sum is 49.

The square root of 661456849 is about 25718.8034130673. The cubic root of 661456849 is about 871.2989136730.

The spelling of 661456849 in words is "six hundred sixty-one million, four hundred fifty-six thousand, eight hundred forty-nine".