21002020434 has 12 divisors (see below), whose sum is σ = 45504377646. Its totient is φ = 7000673472.

The previous prime is 21002020423. The next prime is 21002020447. The reversal of 21002020434 is 43402020012.

21002020434 is a `hidden beast` number, since 210 + 0 + 2 + 0 + 20 + 434 = 666.

It can be written as a sum of positive squares in only one way, i.e., 16564462209 + 4437558225 = 128703^2 + 66615^2 .

It is a Harshad number since it is a multiple of its sum of digits (18), and also a Moran number because the ratio is a prime number: 1166778913 = 21002020434 / (2 + 1 + 0 + 0 + 2 + 0 + 2 + 0 + 4 + 3 + 4).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 583389439 + ... + 583389474.

Almost surely, 2^21002020434 is an apocalyptic number.

21002020434 is an abundant number, since it is smaller than the sum of its proper divisors (24502357212).

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

21002020434 is a wasteful number, since it uses less digits than its factorization.

21002020434 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1166778921 (or 1166778918 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 18.

Adding to 21002020434 its reverse (43402020012), we get a palindrome (64404040446).

The spelling of 21002020434 in words is "twenty-one billion, two million, twenty thousand, four hundred thirty-four".