20199981 has 8 divisors (see below), whose sum is σ = 27559840. Its totient is φ = 13153392.

The previous prime is 20199973. The next prime is 20200013. The reversal of 20199981 is 18999102.

It is a happy number.

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

It is not a de Polignac number, because 20199981 - 2³ = 20199973 is a prime.

It is a super-2 number, since 2×20199981² = 816078464800722, 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 (20199901) 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, 78166 + ... + 78423.

It is an arithmetic number, because the mean of its divisors is an integer number (3444980).

Almost surely, 2^20199981 is an apocalyptic number.

It is an amenable number.

20199981 is a deficient number, since it is larger than the sum of its proper divisors (7359859).

20199981 is a wasteful number, since it uses less digits than its factorization.

20199981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 156635.

The product of its (nonzero) digits is 11664, while the sum is 39.

The square root of 20199981 is about 4494.4388971261. The cubic root of 20199981 is about 272.3434827686.

The spelling of 20199981 in words is "twenty million, one hundred ninety-nine thousand, nine hundred eighty-one".