261721808127162 has 128 divisors (see below), whose sum is σ = 599421446104320. Its totient is φ = 84608775763200.

The previous prime is 261721808127121. The next prime is 261721808127223.

261721808127162 is a `hidden beast` number, since 2 + 61 + 7 + 2 + 180 + 81 + 271 + 62 = 666.

261721808127162 is nontrivially palindromic in base 10.

It is a super-2 number, since 2×261721808127162² (a number of 30 digits) contains 22 as substring.

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

It is a junction number, because it is equal to n+sod(n) for n = 261721808127099 and 261721808127108.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 176456493 + ... + 177933519.

It is an arithmetic number, because the mean of its divisors is an integer number (4682980047690).

Almost surely, 2^{261721808127162} is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261721808127162, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (299710723052160).

261721808127162 is an abundant number, since it is smaller than the sum of its proper divisors (337699637977158).

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

261721808127162 is a wasteful number, since it uses less digits than its factorization.

261721808127162 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1477805 (or 1477799 counting only the distinct ones).

The product of its (nonzero) digits is 1806336, while the sum is 54.

The spelling of 261721808127162 in words is "two hundred sixty-one trillion, seven hundred twenty-one billion, eight hundred eight million, one hundred twenty-seven thousand, one hundred sixty-two".