21155530 has 16 divisors (see below), whose sum is σ = 41541984. Its totient is φ = 7692880.

The previous prime is 21155513. The next prime is 21155543. The reversal of 21155530 is 3555112.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 96052 + ... + 96271.

It is an arithmetic number, because the mean of its divisors is an integer number (2596374).

Almost surely, 2^21155530 is an apocalyptic number.

21155530 is a deficient number, since it is larger than the sum of its proper divisors (20386454).

21155530 is a wasteful number, since it uses less digits than its factorization.

21155530 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 192341.

The product of its (nonzero) digits is 750, while the sum is 22.

The square root of 21155530 is about 4599.5141047724. The cubic root of 21155530 is about 276.5718469928.

It can be divided in two parts, 21 and 155530, that added together give a palindrome (155551).

The spelling of 21155530 in words is "twenty-one million, one hundred fifty-five thousand, five hundred thirty".