117978821 has 2 divisors, whose sum is σ = 117978822. Its totient is φ = 117978820.

The previous prime is 117978811. The next prime is 117978823. The reversal of 117978821 is 128879711.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 104325796 + 13653025 = 10214^2 + 3695^2 .

It is a cyclic number.

It is not a de Polignac number, because 117978821 - 2¹⁴ = 117962437 is a prime.

Together with 117978823, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (117978823) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 58989410 + 58989411.

It is an arithmetic number, because the mean of its divisors is an integer number (58989411).

Almost surely, 2^117978821 is an apocalyptic number.

It is an amenable number.

117978821 is a deficient number, since it is larger than the sum of its proper divisors (1).

117978821 is an equidigital number, since it uses as much as digits as its factorization.

117978821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 56448, while the sum is 44.

The square root of 117978821 is about 10861.8056049627. The cubic root of 117978821 is about 490.4574667067.

The spelling of 117978821 in words is "one hundred seventeen million, nine hundred seventy-eight thousand, eight hundred twenty-one".