21515030 has 32 divisors (see below), whose sum is σ = 43169760. Its totient is φ = 7672320.

The previous prime is 21515017. The next prime is 21515057. The reversal of 21515030 is 3051512.

It is a Harshad number since it is a multiple of its sum of digits (17).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 101 + ... + 6560.

It is an arithmetic number, because the mean of its divisors is an integer number (1349055).

Almost surely, 2^21515030 is an apocalyptic number.

21515030 is an abundant number, since it is smaller than the sum of its proper divisors (21654730).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21515030 is a wasteful number, since it uses less digits than its factorization.

21515030 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6704.

The product of its (nonzero) digits is 150, while the sum is 17.

The square root of 21515030 is about 4638.4296911778. The cubic root of 21515030 is about 278.1296688186.

Adding to 21515030 its reverse (3051512), we get a palindrome (24566542).

The spelling of 21515030 in words is "twenty-one million, five hundred fifteen thousand, thirty".