21018534 has 8 divisors (see below), whose sum is σ = 42037080. Its totient is φ = 7006176.

The previous prime is 21018523. The next prime is 21018539. The reversal of 21018534 is 43581012.

It is a sphenic number, since it is the product of 3 distinct primes.

21018534 is an admirable number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21018539) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1751539 + ... + 1751550.

It is an arithmetic number, because the mean of its divisors is an integer number (5254635).

Almost surely, 2^21018534 is an apocalyptic number.

21018534 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21018534 is a wasteful number, since it uses less digits than its factorization.

21018534 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3503094.

The product of its (nonzero) digits is 960, while the sum is 24.

The square root of 21018534 is about 4584.5974741519. The cubic root of 21018534 is about 275.9735586936.

Adding to 21018534 its reverse (43581012), we get a palindrome (64599546).

The spelling of 21018534 in words is "twenty-one million, eighteen thousand, five hundred thirty-four".