21155516 has 12 divisors (see below), whose sum is σ = 38216640. Its totient is φ = 10236480.

The previous prime is 21155513. The next prime is 21155543. The reversal of 21155516 is 61555112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21155513) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 85181 + ... + 85428.

It is an arithmetic number, because the mean of its divisors is an integer number (3184720).

Almost surely, 2^21155516 is an apocalyptic number.

It is an amenable number.

21155516 is a deficient number, since it is larger than the sum of its proper divisors (17061124).

21155516 is a wasteful number, since it uses less digits than its factorization.

21155516 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 170644 (or 170642 counting only the distinct ones).

The product of its digits is 1500, while the sum is 26.

The square root of 21155516 is about 4599.5125828722. The cubic root of 21155516 is about 276.5717859842.

The spelling of 21155516 in words is "twenty-one million, one hundred fifty-five thousand, five hundred sixteen".