21221559 has 36 divisors (see below), whose sum is σ = 33524400. Its totient is φ = 12925440.

The previous prime is 21221539. The next prime is 21221561. The reversal of 21221559 is 95512212.

It is not a de Polignac number, because 21221559 - 2⁸ = 21221303 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221509) 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 in 35 ways as a sum of consecutive naturals, for example, 106542 + ... + 106740.

Almost surely, 2^21221559 is an apocalyptic number.

21221559 is a deficient number, since it is larger than the sum of its proper divisors (12302841).

21221559 is a wasteful number, since it uses less digits than its factorization.

21221559 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 280 (or 260 counting only the distinct ones).

The product of its digits is 1800, while the sum is 27.

The square root of 21221559 is about 4606.6863361857. The cubic root of 21221559 is about 276.8592863572.

The spelling of 21221559 in words is "twenty-one million, two hundred twenty-one thousand, five hundred fifty-nine".