21736109 has 16 divisors (see below), whose sum is σ = 23390640. Its totient is φ = 20160000.

The previous prime is 21736103. The next prime is 21736111. The reversal of 21736109 is 90163712.

It can be written as a sum of positive squares in 8 ways, for example, as 2111209 + 19624900 = 1453^2 + 4430^2 .

It is a cyclic number.

It is not a de Polignac number, because 21736109 - 2⁴ = 21736093 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21736103) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 119999 + ... + 120179.

It is an arithmetic number, because the mean of its divisors is an integer number (1461915).

Almost surely, 2^21736109 is an apocalyptic number.

21736109 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

It is an amenable number.

21736109 is a deficient number, since it is larger than the sum of its proper divisors (1654531).

21736109 is a wasteful number, since it uses less digits than its factorization.

21736109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 352.

The product of its (nonzero) digits is 2268, while the sum is 29.

The square root of 21736109 is about 4662.2000171593. The cubic root of 21736109 is about 279.0790704405.

The spelling of 21736109 in words is "twenty-one million, seven hundred thirty-six thousand, one hundred nine".