21405394434 has 32 divisors (see below), whose sum is σ = 42934294656. Its totient is φ = 7114573440.

The previous prime is 21405394379. The next prime is 21405394447. The reversal of 21405394434 is 43449350412.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21405394392 and 21405394401.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4839544 + ... + 4843964.

It is an arithmetic number, because the mean of its divisors is an integer number (1341696708).

Almost surely, 2^21405394434 is an apocalyptic number.

21405394434 is an abundant number, since it is smaller than the sum of its proper divisors (21528900222).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21405394434 is a wasteful number, since it uses less digits than its factorization.

21405394434 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6570.

The product of its (nonzero) digits is 207360, while the sum is 39.

The spelling of 21405394434 in words is "twenty-one billion, four hundred five million, three hundred ninety-four thousand, four hundred thirty-four".