681784321 has 3 divisors (see below), whose sum is σ = 681810433. Its totient is φ = 681758210.

The previous prime is 681784309. The next prime is 681784339. The reversal of 681784321 is 123487186.

The square root of 681784321 is 26111.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 681784321 - 2⁵ = 681784289 is a prime.

It is a super-2 number, since 2×681784321² = 929659720722862082, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (681784361) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 13056 + ... + 39166.

Almost surely, 2^681784321 is an apocalyptic number.

681784321 is the 26111-st square number.

681784321 is the 13056-th centered octagonal number.

It is an amenable number.

681784321 is a deficient number, since it is larger than the sum of its proper divisors (26112).

681784321 is an frugal number, since it uses more digits than its factorization.

681784321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52222 (or 26111 counting only the distinct ones).

The product of its digits is 64512, while the sum is 40.

The cubic root of 681784321 is about 880.1344151599.

The spelling of 681784321 in words is "six hundred eighty-one million, seven hundred eighty-four thousand, three hundred twenty-one".