1278900038921 has 2 divisors, whose sum is σ = 1278900038922. Its totient is φ = 1278900038920.

The previous prime is 1278900038909. The next prime is 1278900038963. The reversal of 1278900038921 is 1298300098721.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1256049181696 + 22850857225 = 1120736^2 + 151165^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1278900038921 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1278900038921.

It is not a weakly prime, because it can be changed into another prime (1278900038971) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 639450019460 + 639450019461.

It is an arithmetic number, because the mean of its divisors is an integer number (639450019461).

Almost surely, 2^{1278900038921} is an apocalyptic number.

It is an amenable number.

1278900038921 is a deficient number, since it is larger than the sum of its proper divisors (1).

1278900038921 is an equidigital number, since it uses as much as digits as its factorization.

1278900038921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 435456, while the sum is 50.

The spelling of 1278900038921 in words is "one trillion, two hundred seventy-eight billion, nine hundred million, thirty-eight thousand, nine hundred twenty-one".