1278866421 has 64 divisors (see below), whose sum is σ = 2290892800. Its totient is φ = 688782528.

The previous prime is 1278866411. The next prime is 1278866441. The reversal of 1278866421 is 1246688721.

It is not a de Polignac number, because 1278866421 - 2⁶ = 1278866357 is a prime.

It is a super-2 number, since 2×1278866421² = 3270998645522698482, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1278866411) 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 63 ways as a sum of consecutive naturals, for example, 799995 + ... + 801591.

It is an arithmetic number, because the mean of its divisors is an integer number (35795200).

Almost surely, 2^1278866421 is an apocalyptic number.

It is an amenable number.

1278866421 is a deficient number, since it is larger than the sum of its proper divisors (1012026379).

1278866421 is a wasteful number, since it uses less digits than its factorization.

1278866421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1855 (or 1849 counting only the distinct ones).

The product of its digits is 258048, while the sum is 45.

The square root of 1278866421 is about 35761.2418827982. The cubic root of 1278866421 is about 1085.4464304301.

The spelling of 1278866421 in words is "one billion, two hundred seventy-eight million, eight hundred sixty-six thousand, four hundred twenty-one".