661544369 has 2 divisors, whose sum is σ = 661544370. Its totient is φ = 661544368.

The previous prime is 661544347. The next prime is 661544381. The reversal of 661544369 is 963445166.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 486775969 + 174768400 = 22063^2 + 13220^2 .

It is a cyclic number.

It is not a de Polignac number, because 661544369 - 2¹⁶ = 661478833 is a prime.

It is a super-2 number, since 2×661544369² = 875281904311216322, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (661544339) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330772184 + 330772185.

It is an arithmetic number, because the mean of its divisors is an integer number (330772185).

Almost surely, 2^661544369 is an apocalyptic number.

It is an amenable number.

661544369 is a deficient number, since it is larger than the sum of its proper divisors (1).

661544369 is an equidigital number, since it uses as much as digits as its factorization.

661544369 is an evil number, because the sum of its binary digits is even.

The product of its digits is 466560, while the sum is 44.

The square root of 661544369 is about 25720.5048356365. The cubic root of 661544369 is about 871.3373403257.

The spelling of 661544369 in words is "six hundred sixty-one million, five hundred forty-four thousand, three hundred sixty-nine".