20021047 has 4 divisors (see below), whose sum is σ = 20043936. Its totient is φ = 19998160.

The previous prime is 20021021. The next prime is 20021059. The reversal of 20021047 is 74012002.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20021047 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20021047.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20021147) 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, 10078 + ... + 11899.

It is an arithmetic number, because the mean of its divisors is an integer number (5010984).

Almost surely, 2^20021047 is an apocalyptic number.

20021047 is a deficient number, since it is larger than the sum of its proper divisors (22889).

20021047 is an equidigital number, since it uses as much as digits as its factorization.

20021047 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22888.

The product of its (nonzero) digits is 112, while the sum is 16.

The square root of 20021047 is about 4474.4884623832. The cubic root of 20021047 is about 271.5369455243.

Adding to 20021047 its reverse (74012002), we get a palindrome (94033049).

The spelling of 20021047 in words is "twenty million, twenty-one thousand, forty-seven".