21523404143555 has 4 divisors (see below), whose sum is σ = 25828084972272. Its totient is φ = 17218723314840.

The previous prime is 21523404143551. The next prime is 21523404143573. The reversal of 21523404143555 is 55534140432512.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21523404143555 - 2² = 21523404143551 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21523404143551) 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, 2152340414351 + ... + 2152340414360.

It is an arithmetic number, because the mean of its divisors is an integer number (6457021243068).

Almost surely, 2^{21523404143555} is an apocalyptic number.

21523404143555 is a deficient number, since it is larger than the sum of its proper divisors (4304680828717).

21523404143555 is an equidigital number, since it uses as much as digits as its factorization.

21523404143555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4304680828716.

The product of its (nonzero) digits is 1440000, while the sum is 44.

The spelling of 21523404143555 in words is "twenty-one trillion, five hundred twenty-three billion, four hundred four million, one hundred forty-three thousand, five hundred fifty-five".