21005309454 has 32 divisors (see below), whose sum is σ = 42461314560. Its totient is φ = 6926714112.

The previous prime is 21005309453. The next prime is 21005309473. The reversal of 21005309454 is 45490350012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21005309453) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1753417 + ... + 1765355.

It is an arithmetic number, because the mean of its divisors is an integer number (1326916080).

Almost surely, 2^21005309454 is an apocalyptic number.

21005309454 is an abundant number, since it is smaller than the sum of its proper divisors (21456005106).

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

21005309454 is a wasteful number, since it uses less digits than its factorization.

21005309454 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15064.

The product of its (nonzero) digits is 21600, while the sum is 33.

Adding to 21005309454 its reverse (45490350012), we get a palindrome (66495659466).

The spelling of 21005309454 in words is "twenty-one billion, five million, three hundred nine thousand, four hundred fifty-four".