681961 has 4 divisors (see below), whose sum is σ = 779392. Its totient is φ = 584532.

The previous prime is 681949. The next prime is 681971. The reversal of 681961 is 169186.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 681961 - 2⁷ = 681833 is a prime.

It is a Duffinian number.

681961 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681931) 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, 48705 + ... + 48718.

It is an arithmetic number, because the mean of its divisors is an integer number (194848).

2⁶⁸¹⁹⁶¹ is an apocalyptic number.

It is an amenable number.

681961 is a deficient number, since it is larger than the sum of its proper divisors (97431).

681961 is an equidigital number, since it uses as much as digits as its factorization.

681961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 97430.

The product of its digits is 2592, while the sum is 31.

The square root of 681961 is about 825.8093000203. The cubic root of 681961 is about 88.0210435212.

The spelling of 681961 in words is "six hundred eighty-one thousand, nine hundred sixty-one".