21018770 has 16 divisors (see below), whose sum is σ = 38455128. Its totient is φ = 8269440.

The previous prime is 21018763. The next prime is 21018779. The reversal of 21018770 is 7781012.

It can be written as a sum of positive squares in 4 ways, for example, as 12369289 + 8649481 = 3517^2 + 2941^2 .

It is not an unprimeable number, because it can be changed into a prime (21018779) 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, 16619 + ... + 17838.

Almost surely, 2^21018770 is an apocalyptic number.

21018770 is a deficient number, since it is larger than the sum of its proper divisors (17436358).

21018770 is a wasteful number, since it uses less digits than its factorization.

21018770 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34525.

The product of its (nonzero) digits is 784, while the sum is 26.

The square root of 21018770 is about 4584.6232124352. The cubic root of 21018770 is about 275.9745915838.

Adding to 21018770 its reverse (7781012), we get a palindrome (28799782).

The spelling of 21018770 in words is "twenty-one million, eighteen thousand, seven hundred seventy".