121782109 has 2 divisors, whose sum is σ = 121782110. Its totient is φ = 121782108.

The previous prime is 121782097. The next prime is 121782137. The reversal of 121782109 is 901287121.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 120516484 + 1265625 = 10978^2 + 1125^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-121782109 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (121782179) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 60891054 + 60891055.

It is an arithmetic number, because the mean of its divisors is an integer number (60891055).

Almost surely, 2^121782109 is an apocalyptic number.

It is an amenable number.

121782109 is a deficient number, since it is larger than the sum of its proper divisors (1).

121782109 is an equidigital number, since it uses as much as digits as its factorization.

121782109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2016, while the sum is 31.

The square root of 121782109 is about 11035.4931471140. The cubic root of 121782109 is about 495.6721257601.

The spelling of 121782109 in words is "one hundred twenty-one million, seven hundred eighty-two thousand, one hundred nine".