21258105 has 16 divisors (see below), whose sum is σ = 37105344. Its totient is φ = 10306880.

The previous prime is 21258101. The next prime is 21258121. The reversal of 21258105 is 50185212.

It is not a de Polignac number, because 21258105 - 2² = 21258101 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21258101) 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, 64254 + ... + 64583.

It is an arithmetic number, because the mean of its divisors is an integer number (2319084).

Almost surely, 2^21258105 is an apocalyptic number.

It is an amenable number.

21258105 is a deficient number, since it is larger than the sum of its proper divisors (15847239).

21258105 is a wasteful number, since it uses less digits than its factorization.

21258105 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 128856.

The product of its (nonzero) digits is 800, while the sum is 24.

The square root of 21258105 is about 4610.6512555169. The cubic root of 21258105 is about 277.0181232087.

The spelling of 21258105 in words is "twenty-one million, two hundred fifty-eight thousand, one hundred five".