21318570 has 192 divisors, whose sum is σ = 72334080. Its totient is φ = 4230144.

The previous prime is 21318541. The next prime is 21318599. The reversal of 21318570 is 7581312.

It is an interprime number because it is at equal distance from previous prime (21318541) and next prime (21318599).

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 155542 + ... + 155678.

It is an arithmetic number, because the mean of its divisors is an integer number (376740).

Almost surely, 2^21318570 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21318570, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36167040).

21318570 is an abundant number, since it is smaller than the sum of its proper divisors (51015510).

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

21318570 is a wasteful number, since it uses less digits than its factorization.

21318570 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 189 (or 186 counting only the distinct ones).

The product of its (nonzero) digits is 1680, while the sum is 27.

The square root of 21318570 is about 4617.2036992102. The cubic root of 21318570 is about 277.2805179540.

Adding to 21318570 its reverse (7581312), we get a palindrome (28899882).

It can be divided in two parts, 2131 and 8570, that added together give a palindrome (10701).

The spelling of 21318570 in words is "twenty-one million, three hundred eighteen thousand, five hundred seventy".