681447921 has 96 divisors (see below), whose sum is σ = 1212653568. Its totient is φ = 332640000.

The previous prime is 681447911. The next prime is 681447931. The reversal of 681447921 is 129744186.

It is an interprime number because it is at equal distance from previous prime (681447911) and next prime (681447931).

It is not a de Polignac number, because 681447921 - 2⁵ = 681447889 is a prime.

It is not an unprimeable number, because it can be changed into a prime (681447911) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 3229506 + ... + 3229716.

It is an arithmetic number, because the mean of its divisors is an integer number (12631808).

Almost surely, 2^681447921 is an apocalyptic number.

It is an amenable number.

681447921 is a deficient number, since it is larger than the sum of its proper divisors (531205647).

681447921 is a wasteful number, since it uses less digits than its factorization.

681447921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 315 (or 304 counting only the distinct ones).

The product of its digits is 96768, while the sum is 42.

The square root of 681447921 is about 26104.5574756593. The cubic root of 681447921 is about 879.9896352946.

The spelling of 681447921 in words is "six hundred eighty-one million, four hundred forty-seven thousand, nine hundred twenty-one".