21021020434 has 4 divisors (see below), whose sum is σ = 31531530654. Its totient is φ = 10510510216.

The previous prime is 21021020401. The next prime is 21021020459. The reversal of 21021020434 is 43402012012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 14292919809 + 6728100625 = 119553^2 + 82025^2 .

It is a super-3 number, since 3×21021020434³ (a number of 32 digits) contains 333 as substring.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5255255107 + ... + 5255255110.

Almost surely, 2^21021020434 is an apocalyptic number.

21021020434 is a deficient number, since it is larger than the sum of its proper divisors (10510510220).

21021020434 is a wasteful number, since it uses less digits than its factorization.

21021020434 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10510510219.

The product of its (nonzero) digits is 384, while the sum is 19.

Adding to 21021020434 its reverse (43402012012), we get a palindrome (64423032446).

The spelling of 21021020434 in words is "twenty-one billion, twenty-one million, twenty thousand, four hundred thirty-four".