21723641621491 has 8 divisors (see below), whose sum is σ = 21775834517184. Its totient is φ = 21671462939880.

The previous prime is 21723641621443. The next prime is 21723641621519. The reversal of 21723641621491 is 19412614632712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21723641621491 - 2⁹ = 21723641620979 is a prime.

It is a super-2 number, since 2×21723641621491² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21723641621401) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 490045 + ... + 6609646.

It is an arithmetic number, because the mean of its divisors is an integer number (2721979314648).

Almost surely, 2^{21723641621491} is an apocalyptic number.

21723641621491 is a deficient number, since it is larger than the sum of its proper divisors (52192895693).

21723641621491 is an equidigital number, since it uses as much as digits as its factorization.

21723641621491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7107041.

The product of its digits is 870912, while the sum is 49.

The spelling of 21723641621491 in words is "twenty-one trillion, seven hundred twenty-three billion, six hundred forty-one million, six hundred twenty-one thousand, four hundred ninety-one".