21021440402 has 4 divisors (see below), whose sum is σ = 31532160606. Its totient is φ = 10510720200.

The previous prime is 21021440371. The next prime is 21021440413. The reversal of 21021440402 is 20404412012.

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., 14148864601 + 6872575801 = 118949^2 + 82901^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5255360099 + ... + 5255360102.

Almost surely, 2^21021440402 is an apocalyptic number.

21021440402 is a deficient number, since it is larger than the sum of its proper divisors (10510720204).

21021440402 is a wasteful number, since it uses less digits than its factorization.

21021440402 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10510720203.

The product of its (nonzero) digits is 512, while the sum is 20.

Adding to 21021440402 its reverse (20404412012), we get a palindrome (41425852414).

The spelling of 21021440402 in words is "twenty-one billion, twenty-one million, four hundred forty thousand, four hundred two".