20315211221 has 2 divisors, whose sum is σ = 20315211222. Its totient is φ = 20315211220.

The previous prime is 20315211197. The next prime is 20315211263. The reversal of 20315211221 is 12211251302.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14792640625 + 5522570596 = 121625^2 + 74314^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20315211221 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20315211193 and 20315211202.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20315211281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10157605610 + 10157605611.

It is an arithmetic number, because the mean of its divisors is an integer number (10157605611).

Almost surely, 2^20315211221 is an apocalyptic number.

It is an amenable number.

20315211221 is a deficient number, since it is larger than the sum of its proper divisors (1).

20315211221 is an equidigital number, since it uses as much as digits as its factorization.

20315211221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 240, while the sum is 20.

Adding to 20315211221 its reverse (12211251302), we get a palindrome (32526462523).

The spelling of 20315211221 in words is "twenty billion, three hundred fifteen million, two hundred eleven thousand, two hundred twenty-one".