21541216555420 has 12 divisors (see below), whose sum is σ = 45236554766424. Its totient is φ = 8616486622160.

The previous prime is 21541216555409. The next prime is 21541216555427. The reversal of 21541216555420 is 2455561214512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21541216555427) 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, 538530413866 + ... + 538530413905.

It is an arithmetic number, because the mean of its divisors is an integer number (3769712897202).

Almost surely, 2^{21541216555420} is an apocalyptic number.

21541216555420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21541216555420 is an abundant number, since it is smaller than the sum of its proper divisors (23695338211004).

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

21541216555420 is a wasteful number, since it uses less digits than its factorization.

21541216555420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1077060827780 (or 1077060827778 counting only the distinct ones).

The product of its (nonzero) digits is 480000, while the sum is 43.

Adding to 21541216555420 its reverse (2455561214512), we get a palindrome (23996777769932).

The spelling of 21541216555420 in words is "twenty-one trillion, five hundred forty-one billion, two hundred sixteen million, five hundred fifty-five thousand, four hundred twenty".