21291105 has 16 divisors (see below), whose sum is σ = 37162944. Its totient is φ = 10322880.

The previous prime is 21291097. The next prime is 21291113. The reversal of 21291105 is 50119212.

It is an interprime number because it is at equal distance from previous prime (21291097) and next prime (21291113).

It is not a de Polignac number, because 21291105 - 2³ = 21291097 is a prime.

It is a super-2 number, since 2×21291105² = 906622304242050, which contains 22 as substring.

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, 64354 + ... + 64683.

It is an arithmetic number, because the mean of its divisors is an integer number (2322684).

Almost surely, 2^21291105 is an apocalyptic number.

It is an amenable number.

21291105 is a deficient number, since it is larger than the sum of its proper divisors (15871839).

21291105 is a wasteful number, since it uses less digits than its factorization.

21291105 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 129056.

The product of its (nonzero) digits is 180, while the sum is 21.

The square root of 21291105 is about 4614.2285379032. The cubic root of 21291105 is about 277.1613920439.

It can be divided in two parts, 21291 and 105, that multiplied together give a triangular number (2235555 = T₂₁₁₄).

The spelling of 21291105 in words is "twenty-one million, two hundred ninety-one thousand, one hundred five".