21991941 has 12 divisors (see below), whose sum is σ = 32169280. Its totient is φ = 14475240.

The previous prime is 21991939. The next prime is 21991943. The reversal of 21991941 is 14919912.

It is an interprime number because it is at equal distance from previous prime (21991939) and next prime (21991943).

It is not a de Polignac number, because 21991941 - 2¹ = 21991939 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21991896 and 21991905.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21991943) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 14755 + ... + 16176.

Almost surely, 2^21991941 is an apocalyptic number.

It is an amenable number.

21991941 is a deficient number, since it is larger than the sum of its proper divisors (10177339).

21991941 is a wasteful number, since it uses less digits than its factorization.

21991941 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31016 (or 31013 counting only the distinct ones).

The product of its digits is 5832, while the sum is 36.

The square root of 21991941 is about 4689.5565888472. The cubic root of 21991941 is about 280.1697142884.

The spelling of 21991941 in words is "twenty-one million, nine hundred ninety-one thousand, nine hundred forty-one".