398121817 has 4 divisors (see below), whose sum is σ = 398793780. Its totient is φ = 397449856.

The previous prime is 398121811. The next prime is 398121847. The reversal of 398121817 is 718121893.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 150405696 + 247716121 = 12264^2 + 15739^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-398121817 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 398121817.

It is not an unprimeable number, because it can be changed into a prime (398121811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 335092 + ... + 336277.

It is an arithmetic number, because the mean of its divisors is an integer number (99698445).

Almost surely, 2^398121817 is an apocalyptic number.

It is an amenable number.

398121817 is a deficient number, since it is larger than the sum of its proper divisors (671963).

398121817 is an equidigital number, since it uses as much as digits as its factorization.

398121817 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 671962.

The product of its digits is 24192, while the sum is 40.

The square root of 398121817 is about 19952.9901769133. The cubic root of 398121817 is about 735.6512758267.

The spelling of 398121817 in words is "three hundred ninety-eight million, one hundred twenty-one thousand, eight hundred seventeen".