15221404421 has 2 divisors, whose sum is σ = 15221404422. Its totient is φ = 15221404420.

The previous prime is 15221404409. The next prime is 15221404423. The reversal of 15221404421 is 12440412251.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14965852225 + 255552196 = 122335^2 + 15986^2 .

It is a cyclic number.

It is not a de Polignac number, because 15221404421 - 2²² = 15217210117 is a prime.

Together with 15221404423, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (15221404423) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7610702210 + 7610702211.

It is an arithmetic number, because the mean of its divisors is an integer number (7610702211).

Almost surely, 2^15221404421 is an apocalyptic number.

It is an amenable number.

15221404421 is a deficient number, since it is larger than the sum of its proper divisors (1).

15221404421 is an equidigital number, since it uses as much as digits as its factorization.

15221404421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2560, while the sum is 26.

Adding to 15221404421 its reverse (12440412251), we get a palindrome (27661816672).

The spelling of 15221404421 in words is "fifteen billion, two hundred twenty-one million, four hundred four thousand, four hundred twenty-one".