21221534 has 16 divisors (see below), whose sum is σ = 33051456. Its totient is φ = 10212000.

The previous prime is 21221531. The next prime is 21221539. The reversal of 21221534 is 43512212.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221531) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3884 + ... + 7584.

It is an arithmetic number, because the mean of its divisors is an integer number (2065716).

Almost surely, 2^21221534 is an apocalyptic number.

21221534 is a deficient number, since it is larger than the sum of its proper divisors (11829922).

21221534 is a wasteful number, since it uses less digits than its factorization.

21221534 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3811.

The product of its digits is 480, while the sum is 20.

The square root of 21221534 is about 4606.6836227377. The cubic root of 21221534 is about 276.8591776394.

Adding to 21221534 its reverse (43512212), we get a palindrome (64733746).

The spelling of 21221534 in words is "twenty-one million, two hundred twenty-one thousand, five hundred thirty-four".