661671731477 has 2 divisors, whose sum is σ = 661671731478. Its totient is φ = 661671731476.

The previous prime is 661671731471. The next prime is 661671731521. The reversal of 661671731477 is 774137176166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 593032447396 + 68639284081 = 770086^2 + 261991^2 .

It is a cyclic number.

It is not a de Polignac number, because 661671731477 - 2¹⁰ = 661671730453 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661671731471) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330835865738 + 330835865739.

It is an arithmetic number, because the mean of its divisors is an integer number (330835865739).

Almost surely, 2^661671731477 is an apocalyptic number.

It is an amenable number.

661671731477 is a deficient number, since it is larger than the sum of its proper divisors (1).

661671731477 is an equidigital number, since it uses as much as digits as its factorization.

661671731477 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6223392, while the sum is 56.

The spelling of 661671731477 in words is "six hundred sixty-one billion, six hundred seventy-one million, seven hundred thirty-one thousand, four hundred seventy-seven".