21042320434 has 16 divisors (see below), whose sum is σ = 31806081216. Its totient is φ = 10440543600.

The previous prime is 21042320347. The next prime is 21042320491. The reversal of 21042320434 is 43402324012.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21042320399 and 21042320408.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 106819 + ... + 231289.

It is an arithmetic number, because the mean of its divisors is an integer number (1987880076).

Almost surely, 2^21042320434 is an apocalyptic number.

21042320434 is a deficient number, since it is larger than the sum of its proper divisors (10763760782).

21042320434 is a wasteful number, since it uses less digits than its factorization.

21042320434 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 125121.

The product of its (nonzero) digits is 4608, while the sum is 25.

Adding to 21042320434 its reverse (43402324012), we get a palindrome (64444644446).

The spelling of 21042320434 in words is "twenty-one billion, forty-two million, three hundred twenty thousand, four hundred thirty-four".