1691897 has 2 divisors, whose sum is σ = 1691898. Its totient is φ = 1691896.

The previous prime is 1691869. The next prime is 1691917. The reversal of 1691897 is 7981961.

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., 1308736 + 383161 = 1144^2 + 619^2 .

It is a cyclic number.

It is not a de Polignac number, because 1691897 - 2¹² = 1687801 is a prime.

It is an Ulam number.

It is not a weakly prime, because it can be changed into another prime (1691827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 845948 + 845949.

It is an arithmetic number, because the mean of its divisors is an integer number (845949).

2^1691897 is an apocalyptic number.

It is an amenable number.

1691897 is a deficient number, since it is larger than the sum of its proper divisors (1).

1691897 is an equidigital number, since it uses as much as digits as its factorization.

1691897 is an evil number, because the sum of its binary digits is even.

The product of its digits is 27216, while the sum is 41.

The square root of 1691897 is about 1300.7294107538. The cubic root of 1691897 is about 119.1583936965.

Subtracting 1691897 from its reverse (7981961), we obtain a square (6290064 = 2508²).

The spelling of 1691897 in words is "one million, six hundred ninety-one thousand, eight hundred ninety-seven".