20010021221 has 4 divisors (see below), whose sum is σ = 20010312192. Its totient is φ = 20009730252.

The previous prime is 20010021217. The next prime is 20010021281. The reversal of 20010021221 is 12212001002.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 20010021221 - 2² = 20010021217 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 (20010021281) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21746 + ... + 201228.

It is an arithmetic number, because the mean of its divisors is an integer number (5002578048).

Almost surely, 2^20010021221 is an apocalyptic number.

It is an amenable number.

20010021221 is a deficient number, since it is larger than the sum of its proper divisors (290971).

20010021221 is a wasteful number, since it uses less digits than its factorization.

20010021221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 290970.

The product of its (nonzero) digits is 16, while the sum is 11.

Adding to 20010021221 its reverse (12212001002), we get a palindrome (32222022223).

It can be divided in two parts, 2001002 and 1221, that multiplied together give a palindrome (2443223442).

The spelling of 20010021221 in words is "twenty billion, ten million, twenty-one thousand, two hundred twenty-one".