21991032306 has 20 divisors (see below), whose sum is σ = 49276202382. Its totient is φ = 7330344048.

The previous prime is 21991032229. The next prime is 21991032319. The reversal of 21991032306 is 60323019912.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 15058971225 + 6932061081 = 122715^2 + 83259^2 .

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 in 9 ways as a sum of consecutive naturals, for example, 67873395 + ... + 67873718.

Almost surely, 2^21991032306 is an apocalyptic number.

21991032306 is an abundant number, since it is smaller than the sum of its proper divisors (27285170076).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21991032306 is a wasteful number, since it uses less digits than its factorization.

21991032306 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 135747127 (or 135747118 counting only the distinct ones).

The product of its (nonzero) digits is 17496, while the sum is 36.

The spelling of 21991032306 in words is "twenty-one billion, nine hundred ninety-one million, thirty-two thousand, three hundred six".