261666022544 has 10 divisors (see below), whose sum is σ = 506977918710. Its totient is φ = 130833011264.

The previous prime is 261666022543. The next prime is 261666022559. The reversal of 261666022544 is 445220666162.

It can be written as a sum of positive squares in only one way, i.e., 245540070400 + 16125952144 = 495520^2 + 126988^2 .

It is a junction number, because it is equal to n+sod(n) for n = 261666022495 and 261666022504.

It is not an unprimeable number, because it can be changed into a prime (261666022543) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8177063189 + ... + 8177063220.

It is an arithmetic number, because the mean of its divisors is an integer number (50697791871).

Almost surely, 2^261666022544 is an apocalyptic number.

It is an amenable number.

261666022544 is a deficient number, since it is larger than the sum of its proper divisors (245311896166).

261666022544 is a wasteful number, since it uses less digits than its factorization.

261666022544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16354126417 (or 16354126411 counting only the distinct ones).

The product of its (nonzero) digits is 829440, while the sum is 44.

The spelling of 261666022544 in words is "two hundred sixty-one billion, six hundred sixty-six million, twenty-two thousand, five hundred forty-four".