20942021 has 8 divisors (see below), whose sum is σ = 21749784. Its totient is φ = 20148480.

The previous prime is 20941993. The next prime is 20942023. The reversal of 20942021 is 12024902.

It can be written as a sum of positive squares in 4 ways, for example, as 57121 + 20884900 = 239^2 + 4570^2 .

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 20942021 - 2¹⁸ = 20679877 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 20941984 and 20942002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20942023) 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, 506 + ... + 6491.

It is an arithmetic number, because the mean of its divisors is an integer number (2718723).

Almost surely, 2^20942021 is an apocalyptic number.

It is an amenable number.

20942021 is a deficient number, since it is larger than the sum of its proper divisors (807763).

20942021 is an equidigital number, since it uses as much as digits as its factorization.

20942021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7111.

The product of its (nonzero) digits is 288, while the sum is 20.

The square root of 20942021 is about 4576.2452949989. The cubic root of 20942021 is about 275.6382793807.

Adding to 20942021 its reverse (12024902), we get a palindrome (32966923).

The spelling of 20942021 in words is "twenty million, nine hundred forty-two thousand, twenty-one".