21260072257 has 2 divisors, whose sum is σ = 21260072258. Its totient is φ = 21260072256.

The previous prime is 21260072219. The next prime is 21260072269. The reversal of 21260072257 is 75227006212.

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., 21033990961 + 226081296 = 145031^2 + 15036^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21260072257 is a prime.

It is a super-2 number, since 2×21260072257² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21260072357) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10630036128 + 10630036129.

It is an arithmetic number, because the mean of its divisors is an integer number (10630036129).

Almost surely, 2^21260072257 is an apocalyptic number.

It is an amenable number.

21260072257 is a deficient number, since it is larger than the sum of its proper divisors (1).

21260072257 is an equidigital number, since it uses as much as digits as its factorization.

21260072257 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 23520, while the sum is 34.

Adding to 21260072257 its reverse (75227006212), we get a palindrome (96487078469).

The spelling of 21260072257 in words is "twenty-one billion, two hundred sixty million, seventy-two thousand, two hundred fifty-seven".