1861047981 has 40 divisors (see below), whose sum is σ = 3023180160. Its totient is φ = 1134075168.

The previous prime is 1861047959. The next prime is 1861047983. The reversal of 1861047981 is 1897401681.

It is a happy number.

It is not a de Polignac number, because 1861047981 - 2¹¹ = 1861045933 is a prime.

It is a super-2 number, since 2×1861047981² = 6926999175168352722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1861047983) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 99880 + ... + 117038.

It is an arithmetic number, because the mean of its divisors is an integer number (75579504).

Almost surely, 2^1861047981 is an apocalyptic number.

It is an amenable number.

1861047981 is a deficient number, since it is larger than the sum of its proper divisors (1162132179).

1861047981 is a wasteful number, since it uses less digits than its factorization.

1861047981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17287 (or 17278 counting only the distinct ones).

The product of its (nonzero) digits is 96768, while the sum is 45.

The square root of 1861047981 is about 43139.8653335868. The cubic root of 1861047981 is about 1230.0398737817.

The spelling of 1861047981 in words is "one billion, eight hundred sixty-one million, forty-seven thousand, nine hundred eighty-one".