20730421 has 2 divisors, whose sum is σ = 20730422. Its totient is φ = 20730420.

The previous prime is 20730407. The next prime is 20730433. The reversal of 20730421 is 12403702.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10400625 + 10329796 = 3225^2 + 3214^2 .

It is a cyclic number.

It is not a de Polignac number, because 20730421 - 2⁹ = 20729909 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20730481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10365210 + 10365211.

It is an arithmetic number, because the mean of its divisors is an integer number (10365211).

Almost surely, 2^20730421 is an apocalyptic number.

It is an amenable number.

20730421 is a deficient number, since it is larger than the sum of its proper divisors (1).

20730421 is an equidigital number, since it uses as much as digits as its factorization.

20730421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 336, while the sum is 19.

The square root of 20730421 is about 4553.0672079380. The cubic root of 20730421 is about 274.7067772653.

It can be divided in two parts, 207 and 30421, that added together give a triangular number (30628 = T₂₄₇).

The spelling of 20730421 in words is "twenty million, seven hundred thirty thousand, four hundred twenty-one".