21018465 has 96 divisors (see below), whose sum is σ = 43330560. Its totient is φ = 9331200.

The previous prime is 21018461. The next prime is 21018467. The reversal of 21018465 is 56481012.

It is not a de Polignac number, because 21018465 - 2² = 21018461 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21018461) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 344535 + ... + 344595.

It is an arithmetic number, because the mean of its divisors is an integer number (451360).

Almost surely, 2^21018465 is an apocalyptic number.

It is an amenable number.

21018465 is an abundant number, since it is smaller than the sum of its proper divisors (22312095).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21018465 is a wasteful number, since it uses less digits than its factorization.

21018465 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 135 (or 132 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The square root of 21018465 is about 4584.5899489485. The cubic root of 21018465 is about 275.9732567030.

Adding to 21018465 its reverse (56481012), we get a palindrome (77499477).

The spelling of 21018465 in words is "twenty-one million, eighteen thousand, four hundred sixty-five".