845215908521 has 2 divisors, whose sum is σ = 845215908522. Its totient is φ = 845215908520.

The previous prime is 845215908491. The next prime is 845215908547. The reversal of 845215908521 is 125809512548.

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., 768320618521 + 76895290000 = 876539^2 + 277300^2 .

It is a cyclic number.

It is not a de Polignac number, because 845215908521 - 2¹⁸ = 845215646377 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 845215908521.

It is not a weakly prime, because it can be changed into another prime (845215908421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 422607954260 + 422607954261.

It is an arithmetic number, because the mean of its divisors is an integer number (422607954261).

Almost surely, 2^845215908521 is an apocalyptic number.

It is an amenable number.

845215908521 is a deficient number, since it is larger than the sum of its proper divisors (1).

845215908521 is an equidigital number, since it uses as much as digits as its factorization.

845215908521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1152000, while the sum is 50.

The spelling of 845215908521 in words is "eight hundred forty-five billion, two hundred fifteen million, nine hundred eight thousand, five hundred twenty-one".