20520021 has 8 divisors (see below), whose sum is σ = 27381024. Its totient is φ = 13669520.

The previous prime is 20519977. The next prime is 20520029. The reversal of 20520021 is 12002502.

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

It is a cyclic number.

It is not a de Polignac number, because 20520021 - 2⁷ = 20519893 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20519979 and 20520006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20520029) 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, 5815 + ... + 8651.

It is an arithmetic number, because the mean of its divisors is an integer number (3422628).

Almost surely, 2^20520021 is an apocalyptic number.

It is an amenable number.

20520021 is a deficient number, since it is larger than the sum of its proper divisors (6861003).

20520021 is a wasteful number, since it uses less digits than its factorization.

20520021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5251.

The product of its (nonzero) digits is 40, while the sum is 12.

The square root of 20520021 is about 4529.9029790935. The cubic root of 20520021 is about 273.7742515159.

Adding to 20520021 its reverse (12002502), we get a palindrome (32522523).

The spelling of 20520021 in words is "twenty million, five hundred twenty thousand, twenty-one".