1811971994 has 8 divisors (see below), whose sum is σ = 3106237728. Its totient is φ = 776559420.

The previous prime is 1811971991. The next prime is 1811972021. The reversal of 1811971994 is 4991791181.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (1811971991) 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, 64713272 + ... + 64713299.

It is an arithmetic number, because the mean of its divisors is an integer number (388279716).

Almost surely, 2^1811971994 is an apocalyptic number.

1811971994 is a gapful number since it is divisible by the number (14) formed by its first and last digit.

1811971994 is a deficient number, since it is larger than the sum of its proper divisors (1294265734).

1811971994 is a wasteful number, since it uses less digits than its factorization.

1811971994 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 129426580.

The product of its digits is 163296, while the sum is 50.

The square root of 1811971994 is about 42567.2643471483. The cubic root of 1811971994 is about 1219.1313340703.

The spelling of 1811971994 in words is "one billion, eight hundred eleven million, nine hundred seventy-one thousand, nine hundred ninety-four".