21101212005 has 16 divisors (see below), whose sum is σ = 35747936064. Its totient is φ = 10591980800.

The previous prime is 21101211997. The next prime is 21101212031. The reversal of 21101212005 is 50021210112.

It is not a de Polignac number, because 21101212005 - 2³ = 21101211997 is a prime.

It is a super-2 number, since 2×21101212005² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (15).

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, 41374671 + ... + 41375180.

It is an arithmetic number, because the mean of its divisors is an integer number (2234246004).

Almost surely, 2^21101212005 is an apocalyptic number.

It is an amenable number.

21101212005 is a deficient number, since it is larger than the sum of its proper divisors (14646724059).

21101212005 is a wasteful number, since it uses less digits than its factorization.

21101212005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82749876.

The product of its (nonzero) digits is 40, while the sum is 15.

Adding to 21101212005 its reverse (50021210112), we get a palindrome (71122422117).

The spelling of 21101212005 in words is "twenty-one billion, one hundred one million, two hundred twelve thousand, five".