1398518721 has 12 divisors (see below), whose sum is σ = 2021382480. Its totient is φ = 931745880.

The previous prime is 1398518701. The next prime is 1398518767. The reversal of 1398518721 is 1278158931.

It is not a de Polignac number, because 1398518721 - 2⁵ = 1398518689 is a prime.

It is a super-2 number, since 2×1398518721² = 3911709225974951682, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1398518701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 34995 + ... + 63416.

It is an arithmetic number, because the mean of its divisors is an integer number (168448540).

Almost surely, 2^1398518721 is an apocalyptic number.

It is an amenable number.

1398518721 is a deficient number, since it is larger than the sum of its proper divisors (622863759).

1398518721 is a wasteful number, since it uses less digits than its factorization.

1398518721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 99996 (or 99993 counting only the distinct ones).

The product of its digits is 120960, while the sum is 45.

The square root of 1398518721 is about 37396.7742058055. The cubic root of 1398518721 is about 1118.2942575069.

The spelling of 1398518721 in words is "one billion, three hundred ninety-eight million, five hundred eighteen thousand, seven hundred twenty-one".