21220212157 has 2 divisors, whose sum is σ = 21220212158. Its totient is φ = 21220212156.

The previous prime is 21220212067. The next prime is 21220212179. The reversal of 21220212157 is 75121202212.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15263614116 + 5956598041 = 123546^2 + 77179^2 .

It is a cyclic number.

It is not a de Polignac number, because 21220212157 - 2¹⁵ = 21220179389 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21220219157) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610106078 + 10610106079.

It is an arithmetic number, because the mean of its divisors is an integer number (10610106079).

Almost surely, 2^21220212157 is an apocalyptic number.

It is an amenable number.

21220212157 is a deficient number, since it is larger than the sum of its proper divisors (1).

21220212157 is an equidigital number, since it uses as much as digits as its factorization.

21220212157 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1120, while the sum is 25.

Adding to 21220212157 its reverse (75121202212), we get a palindrome (96341414369).

The spelling of 21220212157 in words is "twenty-one billion, two hundred twenty million, two hundred twelve thousand, one hundred fifty-seven".