681755221 has 4 divisors (see below), whose sum is σ = 779148832. Its totient is φ = 584361612.

The previous prime is 681755203. The next prime is 681755231. The reversal of 681755221 is 122557186.

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 681755221 - 2¹³ = 681747029 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681755201) 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, 48696795 + ... + 48696808.

It is an arithmetic number, because the mean of its divisors is an integer number (194787208).

Almost surely, 2^681755221 is an apocalyptic number.

It is an amenable number.

681755221 is a deficient number, since it is larger than the sum of its proper divisors (97393611).

681755221 is an equidigital number, since it uses as much as digits as its factorization.

681755221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 97393610.

The product of its digits is 33600, while the sum is 37.

The square root of 681755221 is about 26110.4427576401. The cubic root of 681755221 is about 880.1218929809.

The spelling of 681755221 in words is "six hundred eighty-one million, seven hundred fifty-five thousand, two hundred twenty-one".