21991220293 has 16 divisors (see below), whose sum is σ = 27309015040. Its totient is φ = 17281479600.

The previous prime is 21991220269. The next prime is 21991220309. The reversal of 21991220293 is 39202219912.

It is not a de Polignac number, because 21991220293 - 2⁹ = 21991219781 is a prime.

It is a super-2 number, since 2×21991220293² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21991220203) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 2662773 + ... + 2671018.

It is an arithmetic number, because the mean of its divisors is an integer number (1706813440).

Almost surely, 2^21991220293 is an apocalyptic number.

It is an amenable number.

21991220293 is a deficient number, since it is larger than the sum of its proper divisors (5317794747).

21991220293 is a wasteful number, since it uses less digits than its factorization.

21991220293 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5333848.

The product of its (nonzero) digits is 34992, while the sum is 40.

The spelling of 21991220293 in words is "twenty-one billion, nine hundred ninety-one million, two hundred twenty thousand, two hundred ninety-three".