21221499 has 24 divisors (see below), whose sum is σ = 32266560. Its totient is φ = 12366432.

The previous prime is 21221471. The next prime is 21221503. The reversal of 21221499 is 99412212.

It is a happy number.

It is not a de Polignac number, because 21221499 - 2⁵ = 21221467 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21221419) 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 23 ways as a sum of consecutive naturals, for example, 8532 + ... + 10734.

It is an arithmetic number, because the mean of its divisors is an integer number (1344440).

Almost surely, 2^21221499 is an apocalyptic number.

21221499 is a deficient number, since it is larger than the sum of its proper divisors (11045061).

21221499 is a wasteful number, since it uses less digits than its factorization.

21221499 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2251 (or 2238 counting only the distinct ones).

The product of its digits is 2592, while the sum is 30.

The square root of 21221499 is about 4606.6798239079. The cubic root of 21221499 is about 276.8590254343.

The spelling of 21221499 in words is "twenty-one million, two hundred twenty-one thousand, four hundred ninety-nine".