21586321 has 2 divisors, whose sum is σ = 21586322. Its totient is φ = 21586320.

The previous prime is 21586307. The next prime is 21586339. The reversal of 21586321 is 12368512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20657025 + 929296 = 4545^2 + 964^2 .

It is a cyclic number.

It is not a de Polignac number, because 21586321 - 2⁵ = 21586289 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21586321.

It is not a weakly prime, because it can be changed into another prime (21586381) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10793160 + 10793161.

It is an arithmetic number, because the mean of its divisors is an integer number (10793161).

Almost surely, 2^21586321 is an apocalyptic number.

It is an amenable number.

21586321 is a deficient number, since it is larger than the sum of its proper divisors (1).

21586321 is an equidigital number, since it uses as much as digits as its factorization.

21586321 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2880, while the sum is 28.

The square root of 21586321 is about 4646.1081562960. The cubic root of 21586321 is about 278.4365284415.

The spelling of 21586321 in words is "twenty-one million, five hundred eighty-six thousand, three hundred twenty-one".