20012731 has 4 divisors (see below), whose sum is σ = 20286952. Its totient is φ = 19738512.

The previous prime is 20012687. The next prime is 20012743. The reversal of 20012731 is 13721002.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 20012731 - 2⁹ = 20012219 is a prime.

It is a super-2 number, since 2×20012731² = 801018804156722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20012761) 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, 137001 + ... + 137146.

It is an arithmetic number, because the mean of its divisors is an integer number (5071738).

Almost surely, 2^20012731 is an apocalyptic number.

20012731 is a deficient number, since it is larger than the sum of its proper divisors (274221).

20012731 is an equidigital number, since it uses as much as digits as its factorization.

20012731 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 274220.

The product of its (nonzero) digits is 84, while the sum is 16.

The square root of 20012731 is about 4473.5590976313. The cubic root of 20012731 is about 271.4993448608.

Adding to 20012731 its reverse (13721002), we get a palindrome (33733733).

The spelling of 20012731 in words is "twenty million, twelve thousand, seven hundred thirty-one".