21906837811 has 4 divisors (see below), whose sum is σ = 21907342912. Its totient is φ = 21906332712.

The previous prime is 21906837809. The next prime is 21906837817. The reversal of 21906837811 is 11873860912.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21906837811 - 2¹ = 21906837809 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21906837817) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 180675 + ... + 276508.

It is an arithmetic number, because the mean of its divisors is an integer number (5476835728).

Almost surely, 2^21906837811 is an apocalyptic number.

21906837811 is a deficient number, since it is larger than the sum of its proper divisors (505101).

21906837811 is an equidigital number, since it uses as much as digits as its factorization.

21906837811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 505100.

The product of its (nonzero) digits is 145152, while the sum is 46.

The spelling of 21906837811 in words is "twenty-one billion, nine hundred six million, eight hundred thirty-seven thousand, eight hundred eleven".