681044921 has 4 divisors (see below), whose sum is σ = 703014144. Its totient is φ = 659075700.

The previous prime is 681044893. The next prime is 681044989. The reversal of 681044921 is 129440186.

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 681044921 - 2¹⁰ = 681043897 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (681043921) 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, 10984565 + ... + 10984626.

It is an arithmetic number, because the mean of its divisors is an integer number (175753536).

Almost surely, 2^681044921 is an apocalyptic number.

It is an amenable number.

681044921 is a deficient number, since it is larger than the sum of its proper divisors (21969223).

681044921 is a wasteful number, since it uses less digits than its factorization.

681044921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21969222.

The product of its (nonzero) digits is 13824, while the sum is 35.

The square root of 681044921 is about 26096.8373754369. The cubic root of 681044921 is about 879.8161293698.

The spelling of 681044921 in words is "six hundred eighty-one million, forty-four thousand, nine hundred twenty-one".