691964281 has 2 divisors, whose sum is σ = 691964282. Its totient is φ = 691964280.

The previous prime is 691964219. The next prime is 691964291. The reversal of 691964281 is 182469196.

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., 348195600 + 343768681 = 18660^2 + 18541^2 .

It is a cyclic number.

It is not a de Polignac number, because 691964281 - 2¹¹ = 691962233 is a prime.

It is a super-2 number, since 2×691964281² = 957629132359693922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (691964291) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345982140 + 345982141.

It is an arithmetic number, because the mean of its divisors is an integer number (345982141).

Almost surely, 2^691964281 is an apocalyptic number.

It is an amenable number.

691964281 is a deficient number, since it is larger than the sum of its proper divisors (1).

691964281 is an equidigital number, since it uses as much as digits as its factorization.

691964281 is an evil number, because the sum of its binary digits is even.

The product of its digits is 186624, while the sum is 46.

The square root of 691964281 is about 26305.2139508501. The cubic root of 691964281 is about 884.4933233469.

The spelling of 691964281 in words is "six hundred ninety-one million, nine hundred sixty-four thousand, two hundred eighty-one".