20111220251 has 2 divisors, whose sum is σ = 20111220252. Its totient is φ = 20111220250.

The previous prime is 20111220211. The next prime is 20111220307. The reversal of 20111220251 is 15202211102.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20111220251 - 2²⁶ = 20044111387 is a prime.

It is a super-2 number, since 2×20111220251² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20111220211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10055610125 + 10055610126.

It is an arithmetic number, because the mean of its divisors is an integer number (10055610126).

Almost surely, 2^20111220251 is an apocalyptic number.

20111220251 is a deficient number, since it is larger than the sum of its proper divisors (1).

20111220251 is an equidigital number, since it uses as much as digits as its factorization.

20111220251 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 80, while the sum is 17.

Adding to 20111220251 its reverse (15202211102), we get a palindrome (35313431353).

The spelling of 20111220251 in words is "twenty billion, one hundred eleven million, two hundred twenty thousand, two hundred fifty-one".