21321040402 has 4 divisors (see below), whose sum is σ = 31981560606. Its totient is φ = 10660520200.

The previous prime is 21321040397. The next prime is 21321040409. The reversal of 21321040402 is 20404012312.

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., 20385842841 + 935197561 = 142779^2 + 30581^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21321040402.

It is not an unprimeable number, because it can be changed into a prime (21321040409) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5330260099 + ... + 5330260102.

Almost surely, 2^21321040402 is an apocalyptic number.

21321040402 is a deficient number, since it is larger than the sum of its proper divisors (10660520204).

21321040402 is a wasteful number, since it uses less digits than its factorization.

21321040402 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10660520203.

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

Adding to 21321040402 its reverse (20404012312), we get a palindrome (41725052714).

The spelling of 21321040402 in words is "twenty-one billion, three hundred twenty-one million, forty thousand, four hundred two".