266381661 has 32 divisors (see below), whose sum is σ = 438036480. Its totient is φ = 140220864.

The previous prime is 266381651. The next prime is 266381663. The reversal of 266381661 is 166183662.

It is not a de Polignac number, because 266381661 - 2⁵ = 266381629 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (266381663) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 228466 + ... + 229628.

It is an arithmetic number, because the mean of its divisors is an integer number (13688640).

Almost surely, 2^266381661 is an apocalyptic number.

266381661 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

266381661 is a deficient number, since it is larger than the sum of its proper divisors (171654819).

266381661 is a wasteful number, since it uses less digits than its factorization.

266381661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2025.

The product of its digits is 62208, while the sum is 39.

The square root of 266381661 is about 16321.2028049406. The cubic root of 266381661 is about 643.4301997077.

The spelling of 266381661 in words is "two hundred sixty-six million, three hundred eighty-one thousand, six hundred sixty-one".