127801661 has 4 divisors (see below), whose sum is σ = 137632572. Its totient is φ = 117970752.

The previous prime is 127801651. The next prime is 127801669. The reversal of 127801661 is 166108721.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 166108721 = 167 ⋅994663.

It can be written as a sum of positive squares in 2 ways, for example, as 14485636 + 113316025 = 3806^2 + 10645^2 .

It is a cyclic number.

It is not a de Polignac number, because 127801661 - 2¹⁰ = 127800637 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (127801669) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4915436 + ... + 4915461.

It is an arithmetic number, because the mean of its divisors is an integer number (34408143).

Almost surely, 2^127801661 is an apocalyptic number.

It is an amenable number.

127801661 is a deficient number, since it is larger than the sum of its proper divisors (9830911).

127801661 is an equidigital number, since it uses as much as digits as its factorization.

127801661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9830910.

The product of its (nonzero) digits is 4032, while the sum is 32.

The square root of 127801661 is about 11304.9396725502. The cubic root of 127801661 is about 503.7079817671.

It can be divided in two parts, 12780 and 1661, that added together give a palindrome (14441).

The spelling of 127801661 in words is "one hundred twenty-seven million, eight hundred one thousand, six hundred sixty-one".