1187855021 has 2 divisors, whose sum is σ = 1187855022. Its totient is φ = 1187855020.

The previous prime is 1187854999. The next prime is 1187855047. The reversal of 1187855021 is 1205587811.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 680479396 + 507375625 = 26086^2 + 22525^2 .

It is a cyclic number.

It is not a de Polignac number, because 1187855021 - 2²⁶ = 1120746157 is a prime.

It is a super-3 number, since 3×1187855021³ (a number of 28 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1187855621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 593927510 + 593927511.

It is an arithmetic number, because the mean of its divisors is an integer number (593927511).

Almost surely, 2^1187855021 is an apocalyptic number.

It is an amenable number.

1187855021 is a deficient number, since it is larger than the sum of its proper divisors (1).

1187855021 is an equidigital number, since it uses as much as digits as its factorization.

1187855021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 22400, while the sum is 38.

The square root of 1187855021 is about 34465.2726813527. The cubic root of 1187855021 is about 1059.0614158172.

The spelling of 1187855021 in words is "one billion, one hundred eighty-seven million, eight hundred fifty-five thousand, twenty-one".