21776231251 has 2 divisors, whose sum is σ = 21776231252. Its totient is φ = 21776231250.

The previous prime is 21776231221. The next prime is 21776231261. The reversal of 21776231251 is 15213267712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21776231251 - 2⁵ = 21776231219 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21776231251.

It is not a weakly prime, because it can be changed into another prime (21776231221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10888115625 + 10888115626.

It is an arithmetic number, because the mean of its divisors is an integer number (10888115626).

Almost surely, 2^21776231251 is an apocalyptic number.

21776231251 is a deficient number, since it is larger than the sum of its proper divisors (1).

21776231251 is an equidigital number, since it uses as much as digits as its factorization.

21776231251 is an evil number, because the sum of its binary digits is even.

The product of its digits is 35280, while the sum is 37.

Adding to 21776231251 its reverse (15213267712), we get a palindrome (36989498963).

The spelling of 21776231251 in words is "twenty-one billion, seven hundred seventy-six million, two hundred thirty-one thousand, two hundred fifty-one".