121754531781 has 8 divisors (see below), whose sum is σ = 180377084160. Its totient is φ = 81169687836.

The previous prime is 121754531747. The next prime is 121754531803. The reversal of 121754531781 is 187135457121.

121754531781 is a `hidden beast` number, since 1 + 2 + 1 + 7 + 545 + 31 + 78 + 1 = 666.

It is not a de Polignac number, because 121754531781 - 2⁷ = 121754531653 is a prime.

It is a super-2 number, since 2×121754531781² (a number of 23 digits) contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121754531881) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2254713525 + ... + 2254713578.

It is an arithmetic number, because the mean of its divisors is an integer number (22547135520).

Almost surely, 2^121754531781 is an apocalyptic number.

It is an amenable number.

121754531781 is a deficient number, since it is larger than the sum of its proper divisors (58622552379).

121754531781 is an equidigital number, since it uses as much as digits as its factorization.

121754531781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4509427112 (or 4509427106 counting only the distinct ones).

The product of its digits is 235200, while the sum is 45.

The spelling of 121754531781 in words is "one hundred twenty-one billion, seven hundred fifty-four million, five hundred thirty-one thousand, seven hundred eighty-one".