691506281 has 2 divisors, whose sum is σ = 691506282. Its totient is φ = 691506280.

The previous prime is 691506271. The next prime is 691506289. The reversal of 691506281 is 182605196.

691506281 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 471280681 + 220225600 = 21709^2 + 14840^2 .

It is a cyclic number.

It is not a de Polignac number, because 691506281 - 2⁶ = 691506217 is a prime.

It is a super-2 number, since 2×691506281² = 956361873324901922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (691506289) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345753140 + 345753141.

It is an arithmetic number, because the mean of its divisors is an integer number (345753141).

Almost surely, 2^691506281 is an apocalyptic number.

It is an amenable number.

691506281 is a deficient number, since it is larger than the sum of its proper divisors (1).

691506281 is an equidigital number, since it uses as much as digits as its factorization.

691506281 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 25920, while the sum is 38.

The square root of 691506281 is about 26296.5070113884. The cubic root of 691506281 is about 884.2981363207.

The spelling of 691506281 in words is "six hundred ninety-one million, five hundred six thousand, two hundred eighty-one".