661641564707 has 2 divisors, whose sum is σ = 661641564708. Its totient is φ = 661641564706.

The previous prime is 661641564631. The next prime is 661641564763. The reversal of 661641564707 is 707465146166.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 661641564707 - 2¹⁰ = 661641563683 is a prime.

It is not a weakly prime, because it can be changed into another prime (661641564797) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330820782353 + 330820782354.

It is an arithmetic number, because the mean of its divisors is an integer number (330820782354).

Almost surely, 2^661641564707 is an apocalyptic number.

661641564707 is a deficient number, since it is larger than the sum of its proper divisors (1).

661641564707 is an equidigital number, since it uses as much as digits as its factorization.

661641564707 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5080320, while the sum is 53.

The spelling of 661641564707 in words is "six hundred sixty-one billion, six hundred forty-one million, five hundred sixty-four thousand, seven hundred seven".