21221542221 has 32 divisors (see below), whose sum is σ = 33300160128. Its totient is φ = 11876567040.

The previous prime is 21221542217. The next prime is 21221542247. The reversal of 21221542221 is 12224512212.

It is a happy number.

It is not a de Polignac number, because 21221542221 - 2² = 21221542217 is a prime.

It is a super-2 number, since 2×21221542221² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21221542191 and 21221542200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221542261) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 327136 + ... + 386601.

It is an arithmetic number, because the mean of its divisors is an integer number (1040630004).

Almost surely, 2^21221542221 is an apocalyptic number.

It is an amenable number.

21221542221 is a deficient number, since it is larger than the sum of its proper divisors (12078617907).

21221542221 is a wasteful number, since it uses less digits than its factorization.

21221542221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 713821.

The product of its digits is 1280, while the sum is 24.

The spelling of 21221542221 in words is "twenty-one billion, two hundred twenty-one million, five hundred forty-two thousand, two hundred twenty-one".