21001433405 has 4 divisors (see below), whose sum is σ = 25201720092. Its totient is φ = 16801146720.

The previous prime is 21001433393. The next prime is 21001433443. The reversal of 21001433405 is 50433410012.

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 4618969369 + 16382464036 = 67963^2 + 127994^2 .

It is not a de Polignac number, because 21001433405 - 2⁴ = 21001433389 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2100143336 + ... + 2100143345.

It is an arithmetic number, because the mean of its divisors is an integer number (6300430023).

Almost surely, 2^21001433405 is an apocalyptic number.

It is an amenable number.

21001433405 is a deficient number, since it is larger than the sum of its proper divisors (4200286687).

21001433405 is an equidigital number, since it uses as much as digits as its factorization.

21001433405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4200286686.

The product of its (nonzero) digits is 1440, while the sum is 23.

Adding to 21001433405 its reverse (50433410012), we get a palindrome (71434843417).

The spelling of 21001433405 in words is "twenty-one billion, one million, four hundred thirty-three thousand, four hundred five".