2097781 has 4 divisors (see below), whose sum is σ = 2397472. Its totient is φ = 1798092.

The previous prime is 2097779. The next prime is 2097787. The reversal of 2097781 is 1877902.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 2097781 - 2¹ = 2097779 is a prime.

It is a super-2 number, since 2×2097781² = 8801370247922, which contains 22 as substring.

2097781 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2097787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 149835 + ... + 149848.

It is an arithmetic number, because the mean of its divisors is an integer number (599368).

2^2097781 is an apocalyptic number.

It is an amenable number.

2097781 is a deficient number, since it is larger than the sum of its proper divisors (299691).

2097781 is an equidigital number, since it uses as much as digits as its factorization.

2097781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 299690.

The product of its (nonzero) digits is 7056, while the sum is 34.

The square root of 2097781 is about 1448.3718445206. The cubic root of 2097781 is about 128.0127957586.

The spelling of 2097781 in words is "two million, ninety-seven thousand, seven hundred eighty-one".