681491 has 4 divisors (see below), whose sum is σ = 683184. Its totient is φ = 679800.

The previous prime is 681487. The next prime is 681493. The reversal of 681491 is 194186.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 681491 - 2² = 681487 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (681493) 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, 146 + ... + 1176.

It is an arithmetic number, because the mean of its divisors is an integer number (170796).

2⁶⁸¹⁴⁹¹ is an apocalyptic number.

681491 is a deficient number, since it is larger than the sum of its proper divisors (1693).

681491 is a wasteful number, since it uses less digits than its factorization.

681491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1692.

The product of its digits is 1728, while the sum is 29.

The square root of 681491 is about 825.5246816419. The cubic root of 681491 is about 88.0008178299. Note that the first 3 decimals are identical.

The spelling of 681491 in words is "six hundred eighty-one thousand, four hundred ninety-one".