681478921 has 8 divisors (see below), whose sum is σ = 719823104. Its totient is φ = 644157360.

The previous prime is 681478901. The next prime is 681478943. The reversal of 681478921 is 129874186.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 681478921 - 2⁹ = 681478409 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (681478901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 254286 + ... + 256951.

It is an arithmetic number, because the mean of its divisors is an integer number (89977888).

Almost surely, 2^681478921 is an apocalyptic number.

It is an amenable number.

681478921 is a deficient number, since it is larger than the sum of its proper divisors (38344183).

681478921 is a wasteful number, since it uses less digits than its factorization.

681478921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 511311.

The product of its digits is 193536, while the sum is 46.

The square root of 681478921 is about 26105.1512349574. The cubic root of 681478921 is about 880.0029790705.

The spelling of 681478921 in words is "six hundred eighty-one million, four hundred seventy-eight thousand, nine hundred twenty-one".