661331052553 has 2 divisors, whose sum is σ = 661331052554. Its totient is φ = 661331052552.

The previous prime is 661331052539. The next prime is 661331052611. The reversal of 661331052553 is 355250133166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 655123503609 + 6207548944 = 809397^2 + 78788^2 .

It is a cyclic number.

It is not a de Polignac number, because 661331052553 - 2⁵ = 661331052521 is a prime.

It is a super-2 number, since 2×661331052553² (a number of 24 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (661331052953) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330665526276 + 330665526277.

It is an arithmetic number, because the mean of its divisors is an integer number (330665526277).

Almost surely, 2^661331052553 is an apocalyptic number.

It is an amenable number.

661331052553 is a deficient number, since it is larger than the sum of its proper divisors (1).

661331052553 is an equidigital number, since it uses as much as digits as its factorization.

661331052553 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 243000, while the sum is 40.

The spelling of 661331052553 in words is "six hundred sixty-one billion, three hundred thirty-one million, fifty-two thousand, five hundred fifty-three".