1918981 has 4 divisors (see below), whose sum is σ = 2020000. Its totient is φ = 1817964.

The previous prime is 1918979. The next prime is 1918991. The reversal of 1918981 is 1898191.

1918981 = 69² + 70² + ... + 182².

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: 1898191 = 1171 ⋅1621.

It is a cyclic number.

It is not a de Polignac number, because 1918981 - 2¹ = 1918979 is a prime.

It is a super-2 number, since 2×1918981² = 7364976156722, which contains 22 as substring.

It is a Duffinian number.

1918981 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 1918981.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1918921) 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, 50481 + ... + 50518.

It is an arithmetic number, because the mean of its divisors is an integer number (505000).

2^1918981 is an apocalyptic number.

It is an amenable number.

1918981 is a deficient number, since it is larger than the sum of its proper divisors (101019).

1918981 is a wasteful number, since it uses less digits than its factorization.

1918981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 101018.

The product of its digits is 5184, while the sum is 37.

The square root of 1918981 is about 1385.2728973022. The cubic root of 1918981 is about 124.2673083615.

The spelling of 1918981 in words is "one million, nine hundred eighteen thousand, nine hundred eighty-one".