261421167551166 has 64 divisors (see below), whose sum is σ = 664104346329600. Its totient is φ = 74671785353088.

The previous prime is 261421167551119. The next prime is 261421167551213. The reversal of 261421167551166 is 661155761124162.

261421167551166 is a `hidden beast` number, since 2 + 6 + 1 + 4 + 2 + 1 + 1 + 67 + 5 + 511 + 66 = 666.

It is an interprime number because it is at equal distance from previous prime (261421167551119) and next prime (261421167551213).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 91069995 + ... + 93896678.

It is an arithmetic number, because the mean of its divisors is an integer number (10376630411400).

Almost surely, 2^{261421167551166} is an apocalyptic number.

261421167551166 is an abundant number, since it is smaller than the sum of its proper divisors (402683178778434).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

261421167551166 is a wasteful number, since it uses less digits than its factorization.

261421167551166 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 184970430 (or 184970424 counting only the distinct ones).

The product of its digits is 3628800, while the sum is 54.

The spelling of 261421167551166 in words is "two hundred sixty-one trillion, four hundred twenty-one billion, one hundred sixty-seven million, five hundred fifty-one thousand, one hundred sixty-six".