258415256821 has 2 divisors, whose sum is σ = 258415256822. Its totient is φ = 258415256820.

The previous prime is 258415256819. The next prime is 258415256833. The reversal of 258415256821 is 128652514852.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 258414639025 + 617796 = 508345^2 + 786^2 .

It is a cyclic number.

It is not a de Polignac number, because 258415256821 - 2¹ = 258415256819 is a prime.

Together with 258415256819, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (258415256851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 129207628410 + 129207628411.

It is an arithmetic number, because the mean of its divisors is an integer number (129207628411).

Almost surely, 2^258415256821 is an apocalyptic number.

It is an amenable number.

258415256821 is a deficient number, since it is larger than the sum of its proper divisors (1).

258415256821 is an equidigital number, since it uses as much as digits as its factorization.

258415256821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1536000, while the sum is 49.

The spelling of 258415256821 in words is "two hundred fifty-eight billion, four hundred fifteen million, two hundred fifty-six thousand, eight hundred twenty-one".