21661898173440 has 2112 divisors, whose sum is σ = 88177135334400. Its totient is φ = 4533277163520.

The previous prime is 21661898173417. The next prime is 21661898173459. The reversal of 21661898173440 is 4437189816612.

It is a Harshad number since it is a multiple of its sum of digits (60).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 62426219347 + ... + 62426219693.

Almost surely, 2^{21661898173440} is an apocalyptic number.

21661898173440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21661898173440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (44088567667200).

21661898173440 is an abundant number, since it is smaller than the sum of its proper divisors (66515237160960).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21661898173440 is a wasteful number, since it uses less digits than its factorization.

21661898173440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 471 (or 422 counting only the distinct ones).

The product of its (nonzero) digits is 13934592, while the sum is 60.

The spelling of 21661898173440 in words is "twenty-one trillion, six hundred sixty-one billion, eight hundred ninety-eight million, one hundred seventy-three thousand, four hundred forty".