1781397 has 6 divisors (see below), whose sum is σ = 2573142. Its totient is φ = 1187592.

The previous prime is 1781393. The next prime is 1781399. The reversal of 1781397 is 7931871.

It can be written as a sum of positive squares in only one way, i.e., 933156 + 848241 = 966^2 + 921^2 .

It is not a de Polignac number, because 1781397 - 2² = 1781393 is a prime.

1781397 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1781393) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 98958 + ... + 98975.

It is an arithmetic number, because the mean of its divisors is an integer number (428857).

2^1781397 is an apocalyptic number.

It is an amenable number.

1781397 is a deficient number, since it is larger than the sum of its proper divisors (791745).

1781397 is a wasteful number, since it uses less digits than its factorization.

1781397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 197939 (or 197936 counting only the distinct ones).

The product of its digits is 10584, while the sum is 36.

The square root of 1781397 is about 1334.6898516135. The cubic root of 1781397 is about 121.2235241728.

The spelling of 1781397 in words is "one million, seven hundred eighty-one thousand, three hundred ninety-seven".