681721626 has 16 divisors (see below), whose sum is σ = 1377500544. Its totient is φ = 224897664.

The previous prime is 681721603. The next prime is 681721631. The reversal of 681721626 is 626127186.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 585090 + ... + 586253.

It is an arithmetic number, because the mean of its divisors is an integer number (86093784).

Almost surely, 2^681721626 is an apocalyptic number.

681721626 is an abundant number, since it is smaller than the sum of its proper divisors (695778918).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

681721626 is a wasteful number, since it uses less digits than its factorization.

681721626 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1171445.

The product of its digits is 48384, while the sum is 39.

The square root of 681721626 is about 26109.7994247371. The cubic root of 681721626 is about 880.1074360910.

The spelling of 681721626 in words is "six hundred eighty-one million, seven hundred twenty-one thousand, six hundred twenty-six".