21642243661420 has 12 divisors (see below), whose sum is σ = 45448711689024. Its totient is φ = 8656897464560.

The previous prime is 21642243661387. The next prime is 21642243661429. The reversal of 21642243661420 is 2416634224612.

It is a super-4 number, since 4×21642243661420⁴ (a number of 54 digits) contains 4444 as substring.

It is not an unprimeable number, because it can be changed into a prime (21642243661429) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 541056091516 + ... + 541056091555.

It is an arithmetic number, because the mean of its divisors is an integer number (3787392640752).

Almost surely, 2^{21642243661420} is an apocalyptic number.

21642243661420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21642243661420 is an abundant number, since it is smaller than the sum of its proper divisors (23806468027604).

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

21642243661420 is a wasteful number, since it uses less digits than its factorization.

21642243661420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1082112183080 (or 1082112183078 counting only the distinct ones).

The product of its (nonzero) digits is 663552, while the sum is 43.

The spelling of 21642243661420 in words is "twenty-one trillion, six hundred forty-two billion, two hundred forty-three million, six hundred sixty-one thousand, four hundred twenty".