691281 has 8 divisors (see below), whose sum is σ = 1024160. Its totient is φ = 460836.

The previous prime is 691267. The next prime is 691289. The reversal of 691281 is 182196.

It is not a de Polignac number, because 691281 - 2⁷ = 691153 is a prime.

It is a super-2 number, since 2×691281² = 955738841922, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 25603 = 691281 / (6 + 9 + 1 + 2 + 8 + 1).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (691289) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12775 + ... + 12828.

It is an arithmetic number, because the mean of its divisors is an integer number (128020).

2⁶⁹¹²⁸¹ is an apocalyptic number.

It is an amenable number.

691281 is a deficient number, since it is larger than the sum of its proper divisors (332879).

691281 is a wasteful number, since it uses less digits than its factorization.

691281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25612 (or 25606 counting only the distinct ones).

The product of its digits is 864, while the sum is 27.

The square root of 691281 is about 831.4331001349. The cubic root of 691281 is about 88.4202096120.

The spelling of 691281 in words is "six hundred ninety-one thousand, two hundred eighty-one".