21103656005 has 4 divisors (see below), whose sum is σ = 25324387212. Its totient is φ = 16882924800.

The previous prime is 21103655999. The next prime is 21103656019. The reversal of 21103656005 is 50065630112.

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

It can be written as a sum of positive squares in 2 ways, for example, as 5306685409 + 15796970596 = 72847^2 + 125686^2 .

It is not a de Polignac number, because 21103656005 - 2⁶ = 21103655941 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2110365596 + ... + 2110365605.

It is an arithmetic number, because the mean of its divisors is an integer number (6331096803).

Almost surely, 2^21103656005 is an apocalyptic number.

It is an amenable number.

21103656005 is a deficient number, since it is larger than the sum of its proper divisors (4220731207).

21103656005 is an equidigital number, since it uses as much as digits as its factorization.

21103656005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4220731206.

The product of its (nonzero) digits is 5400, while the sum is 29.

The spelling of 21103656005 in words is "twenty-one billion, one hundred three million, six hundred fifty-six thousand, five".