21545520413440 has 36 divisors (see below), whose sum is σ = 51608254368384. Its totient is φ = 8618208164864.

The previous prime is 21545520413429. The next prime is 21545520413441. The reversal of 21545520413440 is 4431402554512.

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 21545520413393 and 21545520413402.

It is not an unprimeable number, because it can be changed into a prime (21545520413441) 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, 8416217632 + ... + 8416220191.

It is an arithmetic number, because the mean of its divisors is an integer number (1433562621344).

Almost surely, 2^{21545520413440} is an apocalyptic number.

21545520413440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21545520413440 is an abundant number, since it is smaller than the sum of its proper divisors (30062733954944).

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

21545520413440 is an equidigital number, since it uses as much as digits as its factorization.

21545520413440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16832437844 (or 16832437830 counting only the distinct ones).

The product of its (nonzero) digits is 384000, while the sum is 40.

Adding to 21545520413440 its reverse (4431402554512), we get a palindrome (25976922967952).

The spelling of 21545520413440 in words is "twenty-one trillion, five hundred forty-five billion, five hundred twenty million, four hundred thirteen thousand, four hundred forty".