21231221002 has 4 divisors (see below), whose sum is σ = 31846831506. Its totient is φ = 10615610500.

The previous prime is 21231220973. The next prime is 21231221003. The reversal of 21231221002 is 20012213212.

It is a happy number.

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., 18335597281 + 2895623721 = 135409^2 + 53811^2 .

It is not an unprimeable number, because it can be changed into a prime (21231221003) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5307805249 + ... + 5307805252.

Almost surely, 2^21231221002 is an apocalyptic number.

21231221002 is a deficient number, since it is larger than the sum of its proper divisors (10615610504).

21231221002 is a wasteful number, since it uses less digits than its factorization.

21231221002 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10615610503.

The product of its (nonzero) digits is 96, while the sum is 16.

Adding to 21231221002 its reverse (20012213212), we get a palindrome (41243434214).

The spelling of 21231221002 in words is "twenty-one billion, two hundred thirty-one million, two hundred twenty-one thousand, two".