21240434355 has 32 divisors (see below), whose sum is σ = 41124340224. Its totient is φ = 9138740736.

The previous prime is 21240434339. The next prime is 21240434357. The reversal of 21240434355 is 55343404212.

It is not a de Polignac number, because 21240434355 - 2⁴ = 21240434339 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21240434357) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 5947917 + ... + 5951486.

It is an arithmetic number, because the mean of its divisors is an integer number (1285135632).

Almost surely, 2^21240434355 is an apocalyptic number.

21240434355 is a deficient number, since it is larger than the sum of its proper divisors (19883905869).

21240434355 is a wasteful number, since it uses less digits than its factorization.

21240434355 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11899435.

The product of its (nonzero) digits is 57600, while the sum is 33.

Adding to 21240434355 its reverse (55343404212), we get a palindrome (76583838567).

The spelling of 21240434355 in words is "twenty-one billion, two hundred forty million, four hundred thirty-four thousand, three hundred fifty-five".