20421277 has 2 divisors, whose sum is σ = 20421278. Its totient is φ = 20421276.

The previous prime is 20421253. The next prime is 20421287. The reversal of 20421277 is 77212402.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18541636 + 1879641 = 4306^2 + 1371^2 .

It is a cyclic number.

It is not a de Polignac number, because 20421277 - 2¹¹ = 20419229 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20421227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10210638 + 10210639.

It is an arithmetic number, because the mean of its divisors is an integer number (10210639).

Almost surely, 2^20421277 is an apocalyptic number.

It is an amenable number.

20421277 is a deficient number, since it is larger than the sum of its proper divisors (1).

20421277 is an equidigital number, since it uses as much as digits as its factorization.

20421277 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1568, while the sum is 25.

The square root of 20421277 is about 4518.9907058988. The cubic root of 20421277 is about 273.3344039551.

Adding to 20421277 its reverse (77212402), we get a palindrome (97633679).

The spelling of 20421277 in words is "twenty million, four hundred twenty-one thousand, two hundred seventy-seven".