21039237493 has 4 divisors (see below), whose sum is σ = 21040281900. Its totient is φ = 21038193088.

The previous prime is 21039237437. The next prime is 21039237539. The reversal of 21039237493 is 39473293012.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 20599999729 + 439237764 = 143527^2 + 20958^2 .

It is a cyclic number.

It is not a de Polignac number, because 21039237493 - 2¹⁷ = 21039106421 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21039232493) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 491380 + ... + 532477.

It is an arithmetic number, because the mean of its divisors is an integer number (5260070475).

Almost surely, 2^21039237493 is an apocalyptic number.

It is an amenable number.

21039237493 is a deficient number, since it is larger than the sum of its proper divisors (1044407).

21039237493 is a wasteful number, since it uses less digits than its factorization.

21039237493 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1044406.

The product of its (nonzero) digits is 244944, while the sum is 43.

The spelling of 21039237493 in words is "twenty-one billion, thirty-nine million, two hundred thirty-seven thousand, four hundred ninety-three".