18421661961 has 24 divisors (see below), whose sum is σ = 26945305920. Its totient is φ = 12126613536.

The previous prime is 18421661959. The next prime is 18421661963. The reversal of 18421661961 is 16916612481.

18421661961 is a `hidden beast` number, since 1 + 8 + 4 + 21 + 6 + 619 + 6 + 1 = 666.

It is an interprime number because it is at equal distance from previous prime (18421661959) and next prime (18421661963).

It is not a de Polignac number, because 18421661961 - 2¹ = 18421661959 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18421661963) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 293035 + ... + 350303.

It is an arithmetic number, because the mean of its divisors is an integer number (1122721080).

Almost surely, 2^18421661961 is an apocalyptic number.

It is an amenable number.

18421661961 is a deficient number, since it is larger than the sum of its proper divisors (8523643959).

18421661961 is a wasteful number, since it uses less digits than its factorization.

18421661961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57725 (or 57722 counting only the distinct ones).

The product of its digits is 124416, while the sum is 45.

The spelling of 18421661961 in words is "eighteen billion, four hundred twenty-one million, six hundred sixty-one thousand, nine hundred sixty-one".