21545521161644 has 12 divisors (see below), whose sum is σ = 37706497578624. Its totient is φ = 10772236139184.

The previous prime is 21545521161643. The next prime is 21545521161691. The reversal of 21545521161644 is 44616112554512.

It is not an unprimeable number, because it can be changed into a prime (21545521161643) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 131017967 + ... + 131182310.

It is an arithmetic number, because the mean of its divisors is an integer number (3142208131552).

Almost surely, 2^{21545521161644} is an apocalyptic number.

It is an amenable number.

21545521161644 is a deficient number, since it is larger than the sum of its proper divisors (16160976416980).

21545521161644 is a wasteful number, since it uses less digits than its factorization.

21545521161644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 262220824 (or 262220822 counting only the distinct ones).

The product of its digits is 1152000, while the sum is 47.

The spelling of 21545521161644 in words is "twenty-one trillion, five hundred forty-five billion, five hundred twenty-one million, one hundred sixty-one thousand, six hundred forty-four".