21243645005 has 16 divisors (see below), whose sum is σ = 27824537664. Its totient is φ = 15441770880.

The previous prime is 21243644987. The next prime is 21243645011. The reversal of 21243645005 is 50054634212.

It is a de Polignac number, because none of the positive numbers 2^k-21243645005 is a prime.

It is a super-2 number, since 2×21243645005² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4262 + ... + 206168.

It is an arithmetic number, because the mean of its divisors is an integer number (1739033604).

Almost surely, 2^21243645005 is an apocalyptic number.

It is an amenable number.

21243645005 is a deficient number, since it is larger than the sum of its proper divisors (6580892659).

21243645005 is a wasteful number, since it uses less digits than its factorization.

21243645005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 203836.

The product of its (nonzero) digits is 28800, while the sum is 32.

The spelling of 21243645005 in words is "twenty-one billion, two hundred forty-three million, six hundred forty-five thousand, five".