21251051377 has 2 divisors, whose sum is σ = 21251051378. Its totient is φ = 21251051376.

The previous prime is 21251051321. The next prime is 21251051401. The reversal of 21251051377 is 77315015212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20015458576 + 1235592801 = 141476^2 + 35151^2 .

It is a cyclic number.

It is not a de Polignac number, because 21251051377 - 2⁷ = 21251051249 is a prime.

It is a super-2 number, since 2×21251051377² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21251001377) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10625525688 + 10625525689.

It is an arithmetic number, because the mean of its divisors is an integer number (10625525689).

Almost surely, 2^21251051377 is an apocalyptic number.

It is an amenable number.

21251051377 is a deficient number, since it is larger than the sum of its proper divisors (1).

21251051377 is an equidigital number, since it uses as much as digits as its factorization.

21251051377 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 14700, while the sum is 34.

Adding to 21251051377 its reverse (77315015212), we get a palindrome (98566066589).

The spelling of 21251051377 in words is "twenty-one billion, two hundred fifty-one million, fifty-one thousand, three hundred seventy-seven".