21408936807 has 4 divisors (see below), whose sum is σ = 28545249080. Its totient is φ = 14272624536.

The previous prime is 21408936799. The next prime is 21408936827. The reversal of 21408936807 is 70863980412.

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

It is not a de Polignac number, because 21408936807 - 2³ = 21408936799 is a prime.

It is a super-2 number, since 2×21408936807² (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 (21408936827) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3568156132 + ... + 3568156137.

It is an arithmetic number, because the mean of its divisors is an integer number (7136312270).

Almost surely, 2^21408936807 is an apocalyptic number.

21408936807 is a deficient number, since it is larger than the sum of its proper divisors (7136312273).

21408936807 is an equidigital number, since it uses as much as digits as its factorization.

21408936807 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7136312272.

The product of its (nonzero) digits is 580608, while the sum is 48.

The spelling of 21408936807 in words is "twenty-one billion, four hundred eight million, nine hundred thirty-six thousand, eight hundred seven".