21518030 has 32 divisors (see below), whose sum is σ = 40981248. Its totient is φ = 8121600.

The previous prime is 21518027. The next prime is 21518033. The reversal of 21518030 is 3081512.

It is an interprime number because it is at equal distance from previous prime (21518027) and next prime (21518033).

It is a junction number, because it is equal to n+sod(n) for n = 21517993 and 21518011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21518033) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11864 + ... + 13556.

It is an arithmetic number, because the mean of its divisors is an integer number (1280664).

Almost surely, 2^21518030 is an apocalyptic number.

21518030 is a deficient number, since it is larger than the sum of its proper divisors (19463218).

21518030 is a wasteful number, since it uses less digits than its factorization.

21518030 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1772.

The product of its (nonzero) digits is 240, while the sum is 20.

The square root of 21518030 is about 4638.7530652105. The cubic root of 21518030 is about 278.1425954445.

Adding to 21518030 its reverse (3081512), we get a palindrome (24599542).

The spelling of 21518030 in words is "twenty-one million, five hundred eighteen thousand, thirty".