18720530 has 16 divisors (see below), whose sum is σ = 33810264. Its totient is φ = 7463040.

The previous prime is 18720467. The next prime is 18720539. The reversal of 18720530 is 3502781.

It can be written as a sum of positive squares in 4 ways, for example, as 3455881 + 15264649 = 1859^2 + 3907^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 18720530.

It is not an unprimeable number, because it can be changed into a prime (18720539) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 140 + ... + 6120.

Almost surely, 2^18720530 is an apocalyptic number.

18720530 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

18720530 is a deficient number, since it is larger than the sum of its proper divisors (15089734).

18720530 is a wasteful number, since it uses less digits than its factorization.

18720530 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6301.

The product of its (nonzero) digits is 1680, while the sum is 26.

The square root of 18720530 is about 4326.7227782699. The cubic root of 18720530 is about 265.5253846536.

The spelling of 18720530 in words is "eighteen million, seven hundred twenty thousand, five hundred thirty".