20207021 has 4 divisors (see below), whose sum is σ = 20318844. Its totient is φ = 20095200.

The previous prime is 20207003. The next prime is 20207023. The reversal of 20207021 is 12070202.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12070202 = 2 ⋅6035101.

It can be written as a sum of positive squares in 2 ways, for example, as 2449225 + 17757796 = 1565^2 + 4214^2 .

It is a cyclic number.

It is not a de Polignac number, because 20207021 - 2¹⁸ = 19944877 is a prime.

It is a Duffinian number.

It is a plaindrome in base 16.

It is a junction number, because it is equal to n+sod(n) for n = 20206987 and 20207005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20207023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 55640 + ... + 56001.

It is an arithmetic number, because the mean of its divisors is an integer number (5079711).

Almost surely, 2^20207021 is an apocalyptic number.

It is an amenable number.

20207021 is a deficient number, since it is larger than the sum of its proper divisors (111823).

20207021 is a wasteful number, since it uses less digits than its factorization.

20207021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 111822.

The product of its (nonzero) digits is 56, while the sum is 14.

The square root of 20207021 is about 4495.2220189886. Note that the first 3 decimals coincide. The cubic root of 20207021 is about 272.3751177064.

Adding to 20207021 its reverse (12070202), we get a palindrome (32277223).

The spelling of 20207021 in words is "twenty million, two hundred seven thousand, twenty-one".