661739247 has 32 divisors (see below), whose sum is σ = 1062936000. Its totient is φ = 404459136.

The previous prime is 661739227. The next prime is 661739251. The reversal of 661739247 is 742937166.

661739247 is a `hidden beast` number, since 6 + 617 + 3 + 9 + 24 + 7 = 666.

It is not a de Polignac number, because 661739247 - 2¹⁴ = 661722863 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661739227) 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 31 ways as a sum of consecutive naturals, for example, 45973 + ... + 58625.

It is an arithmetic number, because the mean of its divisors is an integer number (33216750).

Almost surely, 2^661739247 is an apocalyptic number.

661739247 is a deficient number, since it is larger than the sum of its proper divisors (401196753).

661739247 is a wasteful number, since it uses less digits than its factorization.

661739247 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12824 (or 12818 counting only the distinct ones).

The product of its digits is 381024, while the sum is 45.

The square root of 661739247 is about 25724.2929348894. The cubic root of 661739247 is about 871.4228915577.

The spelling of 661739247 in words is "six hundred sixty-one million, seven hundred thirty-nine thousand, two hundred forty-seven".