21354570 has 64 divisors (see below), whose sum is σ = 57456000. Its totient is φ = 5643648.

The previous prime is 21354551. The next prime is 21354577. The reversal of 21354570 is 7545312.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21354577) 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 31 ways as a sum of consecutive naturals, for example, 37246 + ... + 37814.

It is an arithmetic number, because the mean of its divisors is an integer number (897750).

Almost surely, 2^21354570 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21354570, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28728000).

21354570 is an abundant number, since it is smaller than the sum of its proper divisors (36101430).

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

21354570 is a wasteful number, since it uses less digits than its factorization.

21354570 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 724 (or 718 counting only the distinct ones).

The product of its (nonzero) digits is 4200, while the sum is 27.

The square root of 21354570 is about 4621.1005182748. The cubic root of 21354570 is about 277.4365084839.

Adding to 21354570 its reverse (7545312), we get a palindrome (28899882).

The spelling of 21354570 in words is "twenty-one million, three hundred fifty-four thousand, five hundred seventy".