21105501 has 8 divisors (see below), whose sum is σ = 28671840. Its totient is φ = 13804752.

The previous prime is 21105499. The next prime is 21105509. The reversal of 21105501 is 10550112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21105501 - 2¹ = 21105499 is a prime.

It is a super-2 number, since 2×21105501² = 890884344922002, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21105509) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 66211 + ... + 66528.

It is an arithmetic number, because the mean of its divisors is an integer number (3583980).

Almost surely, 2^21105501 is an apocalyptic number.

It is an amenable number.

21105501 is a deficient number, since it is larger than the sum of its proper divisors (7566339).

21105501 is a wasteful number, since it uses less digits than its factorization.

21105501 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 132795.

The product of its (nonzero) digits is 50, while the sum is 15.

The square root of 21105501 is about 4594.0723764434. The cubic root of 21105501 is about 276.3536607894.

Adding to 21105501 its reverse (10550112), we get a palindrome (31655613).

The spelling of 21105501 in words is "twenty-one million, one hundred five thousand, five hundred one".