1981977 has 4 divisors (see below), whose sum is σ = 2642640. Its totient is φ = 1321316.

The previous prime is 1981963. The next prime is 1981997. The reversal of 1981977 is 7791891.

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, and also an emirpimes, since its reverse is a distinct semiprime: 7791891 = 3 ⋅2597297.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1981977 is a prime.

It is a D-number.

It is not an unprimeable number, because it can be changed into a prime (1981997) 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, 330327 + ... + 330332.

It is an arithmetic number, because the mean of its divisors is an integer number (660660).

2^1981977 is an apocalyptic number.

It is an amenable number.

1981977 is a deficient number, since it is larger than the sum of its proper divisors (660663).

1981977 is an equidigital number, since it uses as much as digits as its factorization.

1981977 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 660662.

The product of its digits is 31752, while the sum is 42.

The square root of 1981977 is about 1407.8270490369. The cubic root of 1981977 is about 125.6125031503.

The spelling of 1981977 in words is "one million, nine hundred eighty-one thousand, nine hundred seventy-seven".