21005084 has 6 divisors (see below), whose sum is σ = 36758904. Its totient is φ = 10502540.

The previous prime is 21005069. The next prime is 21005087. The reversal of 21005084 is 48050012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21005087) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2625632 + ... + 2625639.

It is an arithmetic number, because the mean of its divisors is an integer number (6126484).

Almost surely, 2^21005084 is an apocalyptic number.

It is an amenable number.

21005084 is a deficient number, since it is larger than the sum of its proper divisors (15753820).

21005084 is a wasteful number, since it uses less digits than its factorization.

21005084 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5251275 (or 5251273 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 20.

The square root of 21005084 is about 4583.1303712637. The cubic root of 21005084 is about 275.9146799219.

Adding to 21005084 its reverse (48050012), we get a palindrome (69055096).

The spelling of 21005084 in words is "twenty-one million, five thousand, eighty-four".