21247637911 has 4 divisors (see below), whose sum is σ = 21765873024. Its totient is φ = 20729402800.

The previous prime is 21247637899. The next prime is 21247637921. The reversal of 21247637911 is 11973674212.

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 21247637911 - 2¹¹ = 21247635863 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21247637921) 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, 259117495 + ... + 259117576.

It is an arithmetic number, because the mean of its divisors is an integer number (5441468256).

Almost surely, 2^21247637911 is an apocalyptic number.

21247637911 is a deficient number, since it is larger than the sum of its proper divisors (518235113).

21247637911 is an equidigital number, since it uses as much as digits as its factorization.

21247637911 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 518235112.

The product of its digits is 127008, while the sum is 43.

The spelling of 21247637911 in words is "twenty-one billion, two hundred forty-seven million, six hundred thirty-seven thousand, nine hundred eleven".