661536620154441 has 12 divisors (see below), whose sum is σ = 955553197430260. Its totient is φ = 441024274212480.

The previous prime is 661536620154439. The next prime is 661536620154451. The reversal of 661536620154441 is 144451026635166.

661536620154441 is a `hidden beast` number, since 6 + 6 + 1 + 5 + 3 + 6 + 620 + 1 + 5 + 4 + 4 + 4 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 576037008594441 + 85499611560000 = 24000771^2 + 9246600^2 .

It is not a de Polignac number, because 661536620154441 - 2¹ = 661536620154439 is a prime.

It is a super-2 number, since 2×661536620154441² (a number of 30 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661536620154451) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 24357501 + ... + 43776261.

Almost surely, 2^{661536620154441} is an apocalyptic number.

It is an amenable number.

661536620154441 is a deficient number, since it is larger than the sum of its proper divisors (294016577275819).

661536620154441 is a wasteful number, since it uses less digits than its factorization.

661536620154441 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23203976 (or 23203973 counting only the distinct ones).

The product of its (nonzero) digits is 12441600, while the sum is 54.

The spelling of 661536620154441 in words is "six hundred sixty-one trillion, five hundred thirty-six billion, six hundred twenty million, one hundred fifty-four thousand, four hundred forty-one".