1278257921 has 8 divisors (see below), whose sum is σ = 1299738624. Its totient is φ = 1256955840.

The previous prime is 1278257909. The next prime is 1278257977. The reversal of 1278257921 is 1297528721.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1278257921 - 2⁶ = 1278257857 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1278254921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 30185 + ... + 58886.

It is an arithmetic number, because the mean of its divisors is an integer number (162467328).

Almost surely, 2^1278257921 is an apocalyptic number.

It is an amenable number.

1278257921 is a deficient number, since it is larger than the sum of its proper divisors (21480703).

1278257921 is a wasteful number, since it uses less digits than its factorization.

1278257921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 89311.

The product of its digits is 141120, while the sum is 44.

The square root of 1278257921 is about 35752.7330563693. The cubic root of 1278257921 is about 1085.2742469696.

The spelling of 1278257921 in words is "one billion, two hundred seventy-eight million, two hundred fifty-seven thousand, nine hundred twenty-one".