20299981 has 4 divisors (see below), whose sum is σ = 21861532. Its totient is φ = 18738432.

The previous prime is 20299967. The next prime is 20299991. The reversal of 20299981 is 18999202.

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 8970025 + 11329956 = 2995^2 + 3366^2 .

It is a cyclic number.

It is not a de Polignac number, because 20299981 - 2⁵ = 20299949 is a prime.

It is a super-2 number, since 2×20299981² = 824178457200722, 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 (20299931) 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, 780756 + ... + 780781.

It is an arithmetic number, because the mean of its divisors is an integer number (5465383).

Almost surely, 2^20299981 is an apocalyptic number.

It is an amenable number.

20299981 is a deficient number, since it is larger than the sum of its proper divisors (1561551).

20299981 is a wasteful number, since it uses less digits than its factorization.

20299981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1561550.

The product of its (nonzero) digits is 23328, while the sum is 40.

The square root of 20299981 is about 4505.5500219174. The cubic root of 20299981 is about 272.7921553071.

The spelling of 20299981 in words is "twenty million, two hundred ninety-nine thousand, nine hundred eighty-one".