21420431434 has 4 divisors (see below), whose sum is σ = 32130647154. Its totient is φ = 10710215716.

The previous prime is 21420431419. The next prime is 21420431449. The reversal of 21420431434 is 43413402412.

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

It is an interprime number because it is at equal distance from previous prime (21420431419) and next prime (21420431449).

It can be written as a sum of positive squares in only one way, i.e., 17018507025 + 4401924409 = 130455^2 + 66347^2 .

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 as a sum of consecutive naturals, namely, 5355107857 + ... + 5355107860.

Almost surely, 2^21420431434 is an apocalyptic number.

21420431434 is a deficient number, since it is larger than the sum of its proper divisors (10710215720).

21420431434 is a wasteful number, since it uses less digits than its factorization.

21420431434 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10710215719.

The product of its (nonzero) digits is 9216, while the sum is 28.

Adding to 21420431434 its reverse (43413402412), we get a palindrome (64833833846).

The spelling of 21420431434 in words is "twenty-one billion, four hundred twenty million, four hundred thirty-one thousand, four hundred thirty-four".