15636421 has 2 divisors, whose sum is σ = 15636422. Its totient is φ = 15636420.

The previous prime is 15636419. The next prime is 15636433. The reversal of 15636421 is 12463651.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9235521 + 6400900 = 3039^2 + 2530^2 .

It is a cyclic number.

It is not a de Polignac number, because 15636421 - 2¹ = 15636419 is a prime.

Together with 15636419, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 15636421.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (15636451) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7818210 + 7818211.

It is an arithmetic number, because the mean of its divisors is an integer number (7818211).

Almost surely, 2^15636421 is an apocalyptic number.

It is an amenable number.

15636421 is a deficient number, since it is larger than the sum of its proper divisors (1).

15636421 is an equidigital number, since it uses as much as digits as its factorization.

15636421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4320, while the sum is 28.

The square root of 15636421 is about 3954.2914662427. The cubic root of 15636421 is about 250.0608971649.

The spelling of 15636421 in words is "fifteen million, six hundred thirty-six thousand, four hundred twenty-one".