21515453543451 has 8 divisors (see below), whose sum is σ = 32785453018624. Its totient is φ = 12294544881960.

The previous prime is 21515453543417. The next prime is 21515453543483. The reversal of 21515453543451 is 15434535451512.

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

It is not a de Polignac number, because 21515453543451 - 2⁶ = 21515453543387 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21515453543451.

It is not an unprimeable number, because it can be changed into a prime (21515453543351) 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, 512272703395 + ... + 512272703436.

It is an arithmetic number, because the mean of its divisors is an integer number (4098181627328).

Almost surely, 2^{21515453543451} is an apocalyptic number.

21515453543451 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21515453543451 is a deficient number, since it is larger than the sum of its proper divisors (11269999475173).

21515453543451 is a wasteful number, since it uses less digits than its factorization.

21515453543451 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1024545406841.

The product of its digits is 3600000, while the sum is 48.

Adding to 21515453543451 its reverse (15434535451512), we get a palindrome (36949988994963).

The spelling of 21515453543451 in words is "twenty-one trillion, five hundred fifteen billion, four hundred fifty-three million, five hundred forty-three thousand, four hundred fifty-one".