1245128217 has 4 divisors (see below), whose sum is σ = 1660170960. Its totient is φ = 830085476.

The previous prime is 1245128191. The next prime is 1245128233. The reversal of 1245128217 is 7128215421.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 7128215421 = 3 ⋅2376071807.

It is a cyclic number.

It is not a de Polignac number, because 1245128217 - 2²⁴ = 1228351001 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1245128257) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 207521367 + ... + 207521372.

It is an arithmetic number, because the mean of its divisors is an integer number (415042740).

Almost surely, 2^1245128217 is an apocalyptic number.

It is an amenable number.

1245128217 is a deficient number, since it is larger than the sum of its proper divisors (415042743).

1245128217 is an equidigital number, since it uses as much as digits as its factorization.

1245128217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 415042742.

The product of its digits is 8960, while the sum is 33.

The square root of 1245128217 is about 35286.3743816222. The cubic root of 1245128217 is about 1075.8160645340.

The spelling of 1245128217 in words is "one billion, two hundred forty-five million, one hundred twenty-eight thousand, two hundred seventeen".