1815438981 has 8 divisors (see below), whose sum is σ = 2430714240. Its totient is φ = 1205228192.

The previous prime is 1815438979. The next prime is 1815438983. The reversal of 1815438981 is 1898345181.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (1815438979) and next prime (1815438983).

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

It is a cyclic number.

It is not a de Polignac number, because 1815438981 - 2¹ = 1815438979 is a prime.

It is a super-4 number, since 4×1815438981⁴ (a number of 38 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a self number, because there is not a number n which added to its sum of digits gives 1815438981.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1815438983) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1265280 + ... + 1266713.

It is an arithmetic number, because the mean of its divisors is an integer number (303839280).

Almost surely, 2^1815438981 is an apocalyptic number.

It is an amenable number.

1815438981 is a deficient number, since it is larger than the sum of its proper divisors (615275259).

1815438981 is a wasteful number, since it uses less digits than its factorization.

1815438981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2532235.

The product of its digits is 276480, while the sum is 48.

The square root of 1815438981 is about 42607.9685152907. The cubic root of 1815438981 is about 1219.9083916254.

The spelling of 1815438981 in words is "one billion, eight hundred fifteen million, four hundred thirty-eight thousand, nine hundred eighty-one".