100919981 has 4 divisors (see below), whose sum is σ = 101209500. Its totient is φ = 100630464.

The previous prime is 100919957. The next prime is 100920013. The reversal of 100919981 is 189919001.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 75255625 + 25664356 = 8675^2 + 5066^2 .

It is a cyclic number.

It is not a de Polignac number, because 100919981 - 2²² = 96725677 is a prime.

It is a super-2 number, since 2×100919981² = 20369685130080722, 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 (100919941) 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, 144236 + ... + 144933.

It is an arithmetic number, because the mean of its divisors is an integer number (25302375).

Almost surely, 2^100919981 is an apocalyptic number.

It is an amenable number.

100919981 is a deficient number, since it is larger than the sum of its proper divisors (289519).

100919981 is an equidigital number, since it uses as much as digits as its factorization.

100919981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 289518.

The product of its (nonzero) digits is 5832, while the sum is 38.

The square root of 100919981 is about 10045.8937382395. The cubic root of 100919981 is about 465.5779317376.

The spelling of 100919981 in words is "one hundred million, nine hundred nineteen thousand, nine hundred eighty-one".