21221501 has 8 divisors (see below), whose sum is σ = 24284160. Its totient is φ = 18166608.

The previous prime is 21221471. The next prime is 21221503. The reversal of 21221501 is 10512212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21221501 - 2¹⁰ = 21220477 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221503) 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 7 ways as a sum of consecutive naturals, for example, 6215 + ... + 9003.

It is an arithmetic number, because the mean of its divisors is an integer number (3035520).

Almost surely, 2^21221501 is an apocalyptic number.

It is an amenable number.

21221501 is a deficient number, since it is larger than the sum of its proper divisors (3062659).

21221501 is a wasteful number, since it uses less digits than its factorization.

21221501 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3883.

The product of its (nonzero) digits is 40, while the sum is 14.

The square root of 21221501 is about 4606.6800409840. The cubic root of 21221501 is about 276.8590341318.

Adding to 21221501 its reverse (10512212), we get a palindrome (31733713).

The spelling of 21221501 in words is "twenty-one million, two hundred twenty-one thousand, five hundred one".