20521001221 has 8 divisors (see below), whose sum is σ = 23557743104. Its totient is φ = 17510551920.

The previous prime is 20521001177. The next prime is 20521001231. The reversal of 20521001221 is 12210012502.

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 20521001221 - 2²⁵ = 20487446789 is a prime.

It is a super-2 number, since 2×20521001221² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 20521001195 and 20521001204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20521001231) 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, 6571470 + ... + 6574591.

It is an arithmetic number, because the mean of its divisors is an integer number (2944717888).

Almost surely, 2^20521001221 is an apocalyptic number.

It is an amenable number.

20521001221 is a deficient number, since it is larger than the sum of its proper divisors (3036741883).

20521001221 is a wasteful number, since it uses less digits than its factorization.

20521001221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13146291.

The product of its (nonzero) digits is 80, while the sum is 16.

Adding to 20521001221 its reverse (12210012502), we get a palindrome (32731013723).

The spelling of 20521001221 in words is "twenty billion, five hundred twenty-one million, one thousand, two hundred twenty-one".