661747747 has 2 divisors, whose sum is σ = 661747748. Its totient is φ = 661747746.

The previous prime is 661747721. The next prime is 661747759. The reversal of 661747747 is 747747166.

It is a happy number.

661747747 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 661747747 - 2¹⁵ = 661714979 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 661747747.

It is not a weakly prime, because it can be changed into another prime (661747147) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330873873 + 330873874.

It is an arithmetic number, because the mean of its divisors is an integer number (330873874).

Almost surely, 2^661747747 is an apocalyptic number.

661747747 is a deficient number, since it is larger than the sum of its proper divisors (1).

661747747 is an equidigital number, since it uses as much as digits as its factorization.

661747747 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1382976, while the sum is 49.

The square root of 661747747 is about 25724.4581478405. The cubic root of 661747747 is about 871.4266226662.

The spelling of 661747747 in words is "six hundred sixty-one million, seven hundred forty-seven thousand, seven hundred forty-seven".