121561982155 has 4 divisors (see below), whose sum is σ = 145874378592. Its totient is φ = 97249585720.

The previous prime is 121561982111. The next prime is 121561982173. The reversal of 121561982155 is 551289165121.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 551289165121 = 1487 ⋅370739183.

It is not a de Polignac number, because 121561982155 - 2⁹ = 121561981643 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12156198211 + ... + 12156198220.

It is an arithmetic number, because the mean of its divisors is an integer number (36468594648).

Almost surely, 2^121561982155 is an apocalyptic number.

121561982155 is a deficient number, since it is larger than the sum of its proper divisors (24312396437).

121561982155 is an equidigital number, since it uses as much as digits as its factorization.

121561982155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24312396436.

The product of its digits is 216000, while the sum is 46.

The spelling of 121561982155 in words is "one hundred twenty-one billion, five hundred sixty-one million, nine hundred eighty-two thousand, one hundred fifty-five".