661930315281 has 21 divisors (see below), whose sum is σ = 992474410539. Its totient is φ = 441272232216.

The previous prime is 661930315279. The next prime is 661930315283. The reversal of 661930315281 is 182513039166.

The square root of 661930315281 is 813591.

It is a perfect power (a square), and thus also a powerful number.

661930315281 is a `hidden beast` number, since 6 + 6 + 1 + 93 + 0 + 31 + 528 + 1 = 666.

It is an interprime number because it is at equal distance from previous prime (661930315279) and next prime (661930315283).

It can be written as a sum of positive squares in only one way, i.e., 202945745025 + 458984570256 = 450495^2 + 677484^2 .

It is not a de Polignac number, because 661930315281 - 2¹ = 661930315279 is a prime.

It is a super-2 number, since 2×661930315281² (a number of 24 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (661930315283) by changing a digit.

It is a polite number, since it can be written in 20 ways as a sum of consecutive naturals, for example, 21951891 + ... + 21982023.

Almost surely, 2^661930315281 is an apocalyptic number.

661930315281 is the 813591-st square number.

661930315281 is the 406796-th centered octagonal number.

It is an amenable number.

661930315281 is a deficient number, since it is larger than the sum of its proper divisors (330544095258).

661930315281 is an frugal number, since it uses more digits than its factorization.

661930315281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60284 (or 30136 counting only the distinct ones).

The product of its (nonzero) digits is 233280, while the sum is 45.

The spelling of 661930315281 in words is "six hundred sixty-one billion, nine hundred thirty million, three hundred fifteen thousand, two hundred eighty-one".