15220421 has 2 divisors, whose sum is σ = 15220422. Its totient is φ = 15220420.

The previous prime is 15220391. The next prime is 15220441. The reversal of 15220421 is 12402251.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15124321 + 96100 = 3889^2 + 310^2 .

It is an emirp because it is prime and its reverse (12402251) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 15220421 - 2²² = 11026117 is a prime.

It is a super-2 number, since 2×15220421² = 463322430834482, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 15220421.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (15220441) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7610210 + 7610211.

It is an arithmetic number, because the mean of its divisors is an integer number (7610211).

Almost surely, 2^15220421 is an apocalyptic number.

It is an amenable number.

15220421 is a deficient number, since it is larger than the sum of its proper divisors (1).

15220421 is an equidigital number, since it uses as much as digits as its factorization.

15220421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 160, while the sum is 17.

The square root of 15220421 is about 3901.3357968778. The cubic root of 15220421 is about 247.8233490970.

Adding to 15220421 its reverse (12402251), we get a palindrome (27622672).

The spelling of 15220421 in words is "fifteen million, two hundred twenty thousand, four hundred twenty-one".