20740021 has 2 divisors, whose sum is σ = 20740022. Its totient is φ = 20740020.

The previous prime is 20740009. The next prime is 20740063. The reversal of 20740021 is 12004702.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10817521 + 9922500 = 3289^2 + 3150^2 .

It is a cyclic number.

It is not a de Polignac number, because 20740021 - 2⁷ = 20739893 is a prime.

It is a pancake number, because a pancake can be divided into 20740021 parts by 6440 straight cuts.

It is a junction number, because it is equal to n+sod(n) for n = 20739977 and 20740004.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20744021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10370010 + 10370011.

It is an arithmetic number, because the mean of its divisors is an integer number (10370011).

Almost surely, 2^20740021 is an apocalyptic number.

It is an amenable number.

20740021 is a deficient number, since it is larger than the sum of its proper divisors (1).

20740021 is an equidigital number, since it uses as much as digits as its factorization.

20740021 is an evil number, because the sum of its binary digits is even.

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

The square root of 20740021 is about 4554.1213202988. The cubic root of 20740021 is about 274.7491751514.

Adding to 20740021 its reverse (12004702), we get a palindrome (32744723).

The spelling of 20740021 in words is "twenty million, seven hundred forty thousand, twenty-one".