21340172 has 48 divisors (see below), whose sum is σ = 45299520. Its totient is φ = 8601600.

The previous prime is 21340171. The next prime is 21340177. The reversal of 21340172 is 27104312.

It is not an unprimeable number, because it can be changed into a prime (21340171) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 32972 + ... + 33612.

It is an arithmetic number, because the mean of its divisors is an integer number (943740).

Almost surely, 2^21340172 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21340172, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22649760).

21340172 is an abundant number, since it is smaller than the sum of its proper divisors (23959348).

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

21340172 is a wasteful number, since it uses less digits than its factorization.

21340172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 722 (or 720 counting only the distinct ones).

The product of its (nonzero) digits is 336, while the sum is 20.

The square root of 21340172 is about 4619.5424015805. The cubic root of 21340172 is about 277.3741419906.

Adding to 21340172 its reverse (27104312), we get a palindrome (48444484).

It can be divided in two parts, 21340 and 172, that added together give a palindrome (21512).

The spelling of 21340172 in words is "twenty-one million, three hundred forty thousand, one hundred seventy-two".