20739421 has 2 divisors, whose sum is σ = 20739422. Its totient is φ = 20739420.

The previous prime is 20739347. The next prime is 20739427. The reversal of 20739421 is 12493702.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20602521 + 136900 = 4539^2 + 370^2 .

It is a cyclic number.

It is not a de Polignac number, because 20739421 - 2¹⁷ = 20608349 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20739421.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20739427) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10369710 + 10369711.

It is an arithmetic number, because the mean of its divisors is an integer number (10369711).

Almost surely, 2^20739421 is an apocalyptic number.

It is an amenable number.

20739421 is a deficient number, since it is larger than the sum of its proper divisors (1).

20739421 is an equidigital number, since it uses as much as digits as its factorization.

20739421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3024, while the sum is 28.

The square root of 20739421 is about 4554.0554454244. The cubic root of 20739421 is about 274.7465256668.

The spelling of 20739421 in words is "twenty million, seven hundred thirty-nine thousand, four hundred twenty-one".