21521042454 has 32 divisors (see below), whose sum is σ = 45546084864. Its totient is φ = 6765133760.

The previous prime is 21521042453. The next prime is 21521042467. The reversal of 21521042454 is 45424012512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21521042453) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1088439 + ... + 1108034.

It is an arithmetic number, because the mean of its divisors is an integer number (1423315152).

Almost surely, 2^21521042454 is an apocalyptic number.

21521042454 is an abundant number, since it is smaller than the sum of its proper divisors (24025042410).

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

21521042454 is a wasteful number, since it uses less digits than its factorization.

21521042454 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2196572.

The product of its (nonzero) digits is 12800, while the sum is 30.

Adding to 21521042454 its reverse (45424012512), we get a palindrome (66945054966).

The spelling of 21521042454 in words is "twenty-one billion, five hundred twenty-one million, forty-two thousand, four hundred fifty-four".