21221031209 has 8 divisors (see below), whose sum is σ = 24294643968. Its totient is φ = 18157927680.

The previous prime is 21221031151. The next prime is 21221031211. The reversal of 21221031209 is 90213012212.

It is a happy number.

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 21221031209 - 2⁸ = 21221030953 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21221031509) 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, 2622977 + ... + 2631054.

It is an arithmetic number, because the mean of its divisors is an integer number (3036830496).

Almost surely, 2^21221031209 is an apocalyptic number.

It is an amenable number.

21221031209 is a deficient number, since it is larger than the sum of its proper divisors (3073612759).

21221031209 is an equidigital number, since it uses as much as digits as its factorization.

21221031209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5254615.

The product of its (nonzero) digits is 432, while the sum is 23.

The spelling of 21221031209 in words is "twenty-one billion, two hundred twenty-one million, thirty-one thousand, two hundred nine".