21403512493 has 12 divisors (see below), whose sum is σ = 23537907484. Its totient is φ = 19448035200.

The previous prime is 21403512491. The next prime is 21403512511. The reversal of 21403512493 is 39421530412.

It can be written as a sum of positive squares in 2 ways, for example, as 6284842729 + 15118669764 = 79277^2 + 122958^2 .

It is not a de Polignac number, because 21403512493 - 2¹ = 21403512491 is a prime.

It is a super-2 number, since 2×21403512493² (a number of 21 digits) contains 22 as substring.

It is a hoax number, since the sum of its digits (34) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21403512491) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 205333 + ... + 291493.

Almost surely, 2^21403512493 is an apocalyptic number.

It is an amenable number.

21403512493 is a deficient number, since it is larger than the sum of its proper divisors (2134394991).

21403512493 is a wasteful number, since it uses less digits than its factorization.

21403512493 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 88236 (or 88225 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 34.

The spelling of 21403512493 in words is "twenty-one billion, four hundred three million, five hundred twelve thousand, four hundred ninety-three".