21018376 has 8 divisors (see below), whose sum is σ = 39409470. Its totient is φ = 10509184.

The previous prime is 21018323. The next prime is 21018397. The reversal of 21018376 is 67381012.

It can be written as a sum of positive squares in only one way, i.e., 13032100 + 7986276 = 3610^2 + 2826^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1313641 + ... + 1313656.

Almost surely, 2^21018376 is an apocalyptic number.

It is an amenable number.

21018376 is a deficient number, since it is larger than the sum of its proper divisors (18391094).

21018376 is a wasteful number, since it uses less digits than its factorization.

21018376 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2627303 (or 2627299 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 28.

The square root of 21018376 is about 4584.5802425086. The cubic root of 21018376 is about 275.9728671780.

Adding to 21018376 its reverse (67381012), we get a palindrome (88399388).

The spelling of 21018376 in words is "twenty-one million, eighteen thousand, three hundred seventy-six".