681633737 has 2 divisors, whose sum is σ = 681633738. Its totient is φ = 681633736.

The previous prime is 681633731. The next prime is 681633739. The reversal of 681633737 is 737336186.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 537729721 + 143904016 = 23189^2 + 11996^2 .

It is a cyclic number.

It is not a de Polignac number, because 681633737 - 2⁸ = 681633481 is a prime.

Together with 681633739, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (681633731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340816868 + 340816869.

It is an arithmetic number, because the mean of its divisors is an integer number (340816869).

Almost surely, 2^681633737 is an apocalyptic number.

It is an amenable number.

681633737 is a deficient number, since it is larger than the sum of its proper divisors (1).

681633737 is an equidigital number, since it uses as much as digits as its factorization.

681633737 is an evil number, because the sum of its binary digits is even.

The product of its digits is 381024, while the sum is 44.

The square root of 681633737 is about 26108.1163050880. The cubic root of 681633737 is about 880.0696126922.

The spelling of 681633737 in words is "six hundred eighty-one million, six hundred thirty-three thousand, seven hundred thirty-seven".