1278998721 has 128 divisors (see below), whose sum is σ = 2614886400. Its totient is φ = 596263680.

The previous prime is 1278998681. The next prime is 1278998729.

1278998721 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 1278998721 - 2⁶ = 1278998657 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1278998729) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 999360 + ... + 1000638.

It is an arithmetic number, because the mean of its divisors is an integer number (20428800).

Almost surely, 2^1278998721 is an apocalyptic number.

1278998721 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1278998721 is an abundant number, since it is smaller than the sum of its proper divisors (1335887679).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1278998721 is a wasteful number, since it uses less digits than its factorization.

1278998721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1356 (or 1350 counting only the distinct ones).

The product of its digits is 1016064, while the sum is 54.

The square root of 1278998721 is about 35763.0916029361. The cubic root of 1278998721 is about 1085.4838593094.

It can be divided in two parts, 1278 and 998721, that added together give a palindrome (999999).

The spelling of 1278998721 in words is "one billion, two hundred seventy-eight million, nine hundred ninety-eight thousand, seven hundred twenty-one".