681621733 has 8 divisors (see below), whose sum is σ = 753894008. Its totient is φ = 612183744.

The previous prime is 681621727. The next prime is 681621737. The reversal of 681621733 is 337126186.

It is the 10659-th star number.

It can be written as a sum of positive squares in 4 ways, for example, as 11950849 + 669670884 = 3457^2 + 25878^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-681621733 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (37).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 681621692 and 681621701.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681621737) 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, 708066 + ... + 709027.

It is an arithmetic number, because the mean of its divisors is an integer number (94236751).

Almost surely, 2^681621733 is an apocalyptic number.

It is an amenable number.

681621733 is a deficient number, since it is larger than the sum of its proper divisors (72272275).

681621733 is a wasteful number, since it uses less digits than its factorization.

681621733 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1417143.

The product of its digits is 36288, while the sum is 37.

The square root of 681621733 is about 26107.8864138789. The cubic root of 681621733 is about 880.0644464682.

The spelling of 681621733 in words is "six hundred eighty-one million, six hundred twenty-one thousand, seven hundred thirty-three".