21437204413 has 4 divisors (see below), whose sum is σ = 22128727168. Its totient is φ = 20745681660.

The previous prime is 21437204407. The next prime is 21437204431. The reversal of 21437204413 is 31440273412.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21437204413 - 2³³ = 12847269821 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (31), and also a Moran number because the ratio is a prime number: 691522723 = 21437204413 / (2 + 1 + 4 + 3 + 7 + 2 + 0 + 4 + 4 + 1 + 3).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21437204443) 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, 345761331 + ... + 345761392.

It is an arithmetic number, because the mean of its divisors is an integer number (5532181792).

Almost surely, 2^21437204413 is an apocalyptic number.

It is an amenable number.

21437204413 is a deficient number, since it is larger than the sum of its proper divisors (691522755).

21437204413 is an equidigital number, since it uses as much as digits as its factorization.

21437204413 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 691522754.

The product of its (nonzero) digits is 16128, while the sum is 31.

Adding to 21437204413 its reverse (31440273412), we get a palindrome (52877477825).

The spelling of 21437204413 in words is "twenty-one billion, four hundred thirty-seven million, two hundred four thousand, four hundred thirteen".