21120584257 has 2 divisors, whose sum is σ = 21120584258. Its totient is φ = 21120584256.

The previous prime is 21120584213. The next prime is 21120584273. The reversal of 21120584257 is 75248502112.

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., 15785158321 + 5335425936 = 125639^2 + 73044^2 .

It is a cyclic number.

It is not a de Polignac number, because 21120584257 - 2³¹ = 18973100609 is a prime.

It is not a weakly prime, because it can be changed into another prime (21120584857) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560292128 + 10560292129.

It is an arithmetic number, because the mean of its divisors is an integer number (10560292129).

Almost surely, 2^21120584257 is an apocalyptic number.

It is an amenable number.

21120584257 is a deficient number, since it is larger than the sum of its proper divisors (1).

21120584257 is an equidigital number, since it uses as much as digits as its factorization.

21120584257 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 44800, while the sum is 37.

The spelling of 21120584257 in words is "twenty-one billion, one hundred twenty million, five hundred eighty-four thousand, two hundred fifty-seven".