1981697 has 4 divisors (see below), whose sum is σ = 1988016. Its totient is φ = 1975380.

The previous prime is 1981691. The next prime is 1981699. The reversal of 1981697 is 7961891.

It is a happy number.

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 1981697 - 2¹⁰ = 1980673 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1981691) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2663 + ... + 3324.

It is an arithmetic number, because the mean of its divisors is an integer number (497004).

2^1981697 is an apocalyptic number.

It is an amenable number.

1981697 is a deficient number, since it is larger than the sum of its proper divisors (6319).

1981697 is an equidigital number, since it uses as much as digits as its factorization.

1981697 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6318.

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

The square root of 1981697 is about 1407.7276014911. The cubic root of 1981697 is about 125.6065876499.

The spelling of 1981697 in words is "one million, nine hundred eighty-one thousand, six hundred ninety-seven".