21351105 has 24 divisors (see below), whose sum is σ = 38287080. Its totient is φ = 10993920.

The previous prime is 21351073. The next prime is 21351131. The reversal of 21351105 is 50115312.

21351105 = 578² + 579² + ... + 635².

It can be written as a sum of positive squares in 4 ways, for example, as 1557504 + 19793601 = 1248^2 + 4449^2 .

It is not a de Polignac number, because 21351105 - 2⁵ = 21351073 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6876 + ... + 9485.

It is an arithmetic number, because the mean of its divisors is an integer number (1595295).

Almost surely, 2^21351105 is an apocalyptic number.

It is an amenable number.

21351105 is a deficient number, since it is larger than the sum of its proper divisors (16935975).

21351105 is a wasteful number, since it uses less digits than its factorization.

21351105 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16401 (or 16398 counting only the distinct ones).

The product of its (nonzero) digits is 150, while the sum is 18.

The square root of 21351105 is about 4620.7255923718. The cubic root of 21351105 is about 277.4215020239.

Adding to 21351105 its reverse (50115312), we get a palindrome (71466417).

It can be divided in two parts, 2135 and 1105, that added together give a triangular number (3240 = T₈₀).

The spelling of 21351105 in words is "twenty-one million, three hundred fifty-one thousand, one hundred five".