689971081 has 2 divisors, whose sum is σ = 689971082. Its totient is φ = 689971080.

The previous prime is 689971063. The next prime is 689971099. The reversal of 689971081 is 180179986.

It is a balanced prime because it is at equal distance from previous prime (689971063) and next prime (689971099).

It can be written as a sum of positive squares in only one way, i.e., 684607225 + 5363856 = 26165^2 + 2316^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-689971081 is a prime.

It is a super-2 number, since 2×689971081² = 952120185232617122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (689971481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 344985540 + 344985541.

It is an arithmetic number, because the mean of its divisors is an integer number (344985541).

Almost surely, 2^689971081 is an apocalyptic number.

It is an amenable number.

689971081 is a deficient number, since it is larger than the sum of its proper divisors (1).

689971081 is an equidigital number, since it uses as much as digits as its factorization.

689971081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 217728, while the sum is 49.

The square root of 689971081 is about 26267.3006036022. The cubic root of 689971081 is about 883.6432469297.

The spelling of 689971081 in words is "six hundred eighty-nine million, nine hundred seventy-one thousand, eighty-one".