661244287 has 4 divisors (see below), whose sum is σ = 721357416. Its totient is φ = 601131160.

The previous prime is 661244261. The next prime is 661244321. The reversal of 661244287 is 782442166.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 661244287 - 2⁷ = 661244159 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661244237) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30056548 + ... + 30056569.

It is an arithmetic number, because the mean of its divisors is an integer number (180339354).

Almost surely, 2^661244287 is an apocalyptic number.

661244287 is a deficient number, since it is larger than the sum of its proper divisors (60113129).

661244287 is a wasteful number, since it uses less digits than its factorization.

661244287 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60113128.

The product of its digits is 129024, while the sum is 40.

The square root of 661244287 is about 25714.6706570393. The cubic root of 661244287 is about 871.2055717907.

The spelling of 661244287 in words is "six hundred sixty-one million, two hundred forty-four thousand, two hundred eighty-seven".