21612270 has 64 divisors (see below), whose sum is σ = 56733696. Its totient is φ = 5245440.

The previous prime is 21612259. The next prime is 21612277. The reversal of 21612270 is 7221612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21612277) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 15127 + ... + 16493.

It is an arithmetic number, because the mean of its divisors is an integer number (886464).

Almost surely, 2^21612270 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21612270, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28366848).

21612270 is an abundant number, since it is smaller than the sum of its proper divisors (35121426).

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

21612270 is a wasteful number, since it uses less digits than its factorization.

21612270 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1425.

The product of its (nonzero) digits is 336, while the sum is 21.

The square root of 21612270 is about 4648.8998698617. The cubic root of 21612270 is about 278.5480536412.

Adding to 21612270 its reverse (7221612), we get a palindrome (28833882).

The spelling of 21612270 in words is "twenty-one million, six hundred twelve thousand, two hundred seventy".