681749449 has 2 divisors, whose sum is σ = 681749450. Its totient is φ = 681749448.

The previous prime is 681749423. The next prime is 681749459. The reversal of 681749449 is 944947186.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 348942400 + 332807049 = 18680^2 + 18243^2 .

It is a cyclic number.

It is not a de Polignac number, because 681749449 - 2¹¹ = 681747401 is a prime.

It is a super-2 number, since 2×681749449² = 929564622423607202, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 681749396 and 681749405.

It is not a weakly prime, because it can be changed into another prime (681749459) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340874724 + 340874725.

It is an arithmetic number, because the mean of its divisors is an integer number (340874725).

Almost surely, 2^681749449 is an apocalyptic number.

It is an amenable number.

681749449 is a deficient number, since it is larger than the sum of its proper divisors (1).

681749449 is an equidigital number, since it uses as much as digits as its factorization.

681749449 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1741824, while the sum is 52.

The square root of 681749449 is about 26110.3322269174. The cubic root of 681749449 is about 880.1194091579.

The spelling of 681749449 in words is "six hundred eighty-one million, seven hundred forty-nine thousand, four hundred forty-nine".