21155005 has 8 divisors (see below), whose sum is σ = 25454592. Its totient is φ = 16878288.

The previous prime is 21154997. The next prime is 21155027. The reversal of 21155005 is 50055112.

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

It is a cyclic number.

It is not a de Polignac number, because 21155005 - 2³ = 21154997 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3609 + ... + 7438.

It is an arithmetic number, because the mean of its divisors is an integer number (3181824).

Almost surely, 2^21155005 is an apocalyptic number.

It is an amenable number.

21155005 is a deficient number, since it is larger than the sum of its proper divisors (4299587).

21155005 is a wasteful number, since it uses less digits than its factorization.

21155005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11435.

The product of its (nonzero) digits is 250, while the sum is 19.

The square root of 21155005 is about 4599.4570331725. The cubic root of 21155005 is about 276.5695591525.

The spelling of 21155005 in words is "twenty-one million, one hundred fifty-five thousand, five".