21389721498 has 48 divisors (see below), whose sum is σ = 46771883496. Its totient is φ = 7064340480.

The previous prime is 21389721449. The next prime is 21389721499. The reversal of 21389721498 is 89412798312.

21389721498 is a `hidden beast` number, since 2 + 1 + 3 + 89 + 72 + 1 + 498 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 11125397529 + 10264323969 = 105477^2 + 101313^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21389721499) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1326090 + ... + 1342122.

Almost surely, 2^21389721498 is an apocalyptic number.

21389721498 is an abundant number, since it is smaller than the sum of its proper divisors (25382161998).

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

21389721498 is a wasteful number, since it uses less digits than its factorization.

21389721498 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16719 (or 16716 counting only the distinct ones).

The product of its digits is 1741824, while the sum is 54.

The spelling of 21389721498 in words is "twenty-one billion, three hundred eighty-nine million, seven hundred twenty-one thousand, four hundred ninety-eight".