1000009981 has 4 divisors (see below), whose sum is σ = 1000173600. Its totient is φ = 999846364.

The previous prime is 1000009961. The next prime is 1000009999. The reversal of 1000009981 is 1899000001.

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.

It is a cyclic number.

It is not a de Polignac number, because 1000009981 - 2⁹ = 1000009469 is a prime.

It is a super-2 number, since 2×1000009981² = 2000039924199240722, 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 (1000009961) 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, 72271 + ... + 84988.

It is an arithmetic number, because the mean of its divisors is an integer number (250043400).

Almost surely, 2^1000009981 is an apocalyptic number.

It is an amenable number.

1000009981 is a deficient number, since it is larger than the sum of its proper divisors (163619).

1000009981 is an equidigital number, since it uses as much as digits as its factorization.

1000009981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 163618.

The product of its (nonzero) digits is 648, while the sum is 28.

The square root of 1000009981 is about 31622.9344147566. The cubic root of 1000009981 is about 1000.0033269889.

Adding to 1000009981 its reverse (1899000001), we get a palindrome (2899009982).

The spelling of 1000009981 in words is "one billion, nine thousand, nine hundred eighty-one".