21380498257 has 2 divisors, whose sum is σ = 21380498258. Its totient is φ = 21380498256.

The previous prime is 21380498207. The next prime is 21380498291. The reversal of 21380498257 is 75289408312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19595520256 + 1784978001 = 139984^2 + 42249^2 .

It is a cyclic number.

It is not a de Polignac number, because 21380498257 - 2¹¹ = 21380496209 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21380498257.

It is not a weakly prime, because it can be changed into another prime (21380498207) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10690249128 + 10690249129.

It is an arithmetic number, because the mean of its divisors is an integer number (10690249129).

Almost surely, 2^21380498257 is an apocalyptic number.

It is an amenable number.

21380498257 is a deficient number, since it is larger than the sum of its proper divisors (1).

21380498257 is an equidigital number, since it uses as much as digits as its factorization.

21380498257 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 967680, while the sum is 49.

The spelling of 21380498257 in words is "twenty-one billion, three hundred eighty million, four hundred ninety-eight thousand, two hundred fifty-seven".