21216631234 has 4 divisors (see below), whose sum is σ = 31824946854. Its totient is φ = 10608315616.

The previous prime is 21216631223. The next prime is 21216631259. The reversal of 21216631234 is 43213661212.

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., 17583555609 + 3633075625 = 132603^2 + 60275^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21216631196 and 21216631205.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5304157807 + ... + 5304157810.

Almost surely, 2^21216631234 is an apocalyptic number.

21216631234 is a deficient number, since it is larger than the sum of its proper divisors (10608315620).

21216631234 is a wasteful number, since it uses less digits than its factorization.

21216631234 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10608315619.

The product of its digits is 10368, while the sum is 31.

The spelling of 21216631234 in words is "twenty-one billion, two hundred sixteen million, six hundred thirty-one thousand, two hundred thirty-four".