18721970 has 16 divisors (see below), whose sum is σ = 34048728. Its totient is φ = 7411200.

The previous prime is 18721903. The next prime is 18721979. The reversal of 18721970 is 7912781.

It can be written as a sum of positive squares in 4 ways, for example, as 15077689 + 3644281 = 3883^2 + 1909^2 .

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 18721970.

It is not an unprimeable number, because it can be changed into a prime (18721979) 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 7 ways as a sum of consecutive naturals, for example, 8681 + ... + 10620.

Almost surely, 2^18721970 is an apocalyptic number.

18721970 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

18721970 is a deficient number, since it is larger than the sum of its proper divisors (15326758).

18721970 is a wasteful number, since it uses less digits than its factorization.

18721970 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19405.

The product of its (nonzero) digits is 7056, while the sum is 35.

The square root of 18721970 is about 4326.8891827732. The cubic root of 18721970 is about 265.5321926295.

It can be divided in two parts, 18721 and 970, that added together give a palindrome (19691).

The spelling of 18721970 in words is "eighteen million, seven hundred twenty-one thousand, nine hundred seventy".