1778981 has 4 divisors (see below), whose sum is σ = 1856352. Its totient is φ = 1701612.

The previous prime is 1778977. The next prime is 1778983. The reversal of 1778981 is 1898771.

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: 1898771 = 7 ⋅271253.

It is a cyclic number.

It is not a de Polignac number, because 1778981 - 2² = 1778977 is a prime.

It is a super-2 number, since 2×1778981² = 6329546796722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1778983) 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, 38651 + ... + 38696.

It is an arithmetic number, because the mean of its divisors is an integer number (464088).

2^1778981 is an apocalyptic number.

It is an amenable number.

1778981 is a deficient number, since it is larger than the sum of its proper divisors (77371).

1778981 is an equidigital number, since it uses as much as digits as its factorization.

1778981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77370.

The product of its digits is 28224, while the sum is 41.

The square root of 1778981 is about 1333.7844653466. The cubic root of 1778981 is about 121.1686966905.

The spelling of 1778981 in words is "one million, seven hundred seventy-eight thousand, nine hundred eighty-one".