21101308409 has 4 divisors (see below), whose sum is σ = 21101599860. Its totient is φ = 21101016960.

The previous prime is 21101308399. The next prime is 21101308433. The reversal of 21101308409 is 90480310112.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 16128238009 + 4973070400 = 126997^2 + 70520^2 .

It is a cyclic number.

It is not a de Polignac number, because 21101308409 - 2³² = 16806341113 is a prime.

It is a super-2 number, since 2×21101308409² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21101308469) 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, 55469 + ... + 212789.

It is an arithmetic number, because the mean of its divisors is an integer number (5275399965).

Almost surely, 2^21101308409 is an apocalyptic number.

It is an amenable number.

21101308409 is a deficient number, since it is larger than the sum of its proper divisors (291451).

21101308409 is a wasteful number, since it uses less digits than its factorization.

21101308409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 291450.

The product of its (nonzero) digits is 1728, while the sum is 29.

The spelling of 21101308409 in words is "twenty-one billion, one hundred one million, three hundred eight thousand, four hundred nine".