1187297378921 has 2 divisors, whose sum is σ = 1187297378922. Its totient is φ = 1187297378920.

The previous prime is 1187297378909. The next prime is 1187297379007. The reversal of 1187297378921 is 1298737927811.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 876964823296 + 310332555625 = 936464^2 + 557075^2 .

It is an emirp because it is prime and its reverse (1298737927811) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1187297378921 is a prime.

It is not a weakly prime, because it can be changed into another prime (1187297378521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 593648689460 + 593648689461.

It is an arithmetic number, because the mean of its divisors is an integer number (593648689461).

Almost surely, 2^{1187297378921} is an apocalyptic number.

It is an amenable number.

1187297378921 is a deficient number, since it is larger than the sum of its proper divisors (1).

1187297378921 is an equidigital number, since it uses as much as digits as its factorization.

1187297378921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 21337344, while the sum is 65.

The spelling of 1187297378921 in words is "one trillion, one hundred eighty-seven billion, two hundred ninety-seven million, three hundred seventy-eight thousand, nine hundred twenty-one".