661556151651631 has 2 divisors, whose sum is σ = 661556151651632. Its totient is φ = 661556151651630.

The previous prime is 661556151651607. The next prime is 661556151651667. The reversal of 661556151651631 is 136156151655166.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 661556151651631 - 2⁵ = 661556151651599 is a prime.

It is a super-2 number, since 2×661556151651631² (a number of 30 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661556151651331) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330778075825815 + 330778075825816.

It is an arithmetic number, because the mean of its divisors is an integer number (330778075825816).

Almost surely, 2^{661556151651631} is an apocalyptic number.

661556151651631 is a deficient number, since it is larger than the sum of its proper divisors (1).

661556151651631 is an equidigital number, since it uses as much as digits as its factorization.

661556151651631 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 14580000, while the sum is 58.

The spelling of 661556151651631 in words is "six hundred sixty-one trillion, five hundred fifty-six billion, one hundred fifty-one million, six hundred fifty-one thousand, six hundred thirty-one".