21201642 has 64 divisors (see below), whose sum is σ = 58752000. Its totient is φ = 5505840.

The previous prime is 21201641. The next prime is 21201647. The reversal of 21201642 is 24610212.

21201642 is a `hidden beast` number, since 2 + 1 + 20 + 1 + 642 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (21201641) 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, 1609 + ... + 6707.

It is an arithmetic number, because the mean of its divisors is an integer number (918000).

Almost surely, 2^21201642 is an apocalyptic number.

21201642 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 21201642, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29376000).

21201642 is an abundant number, since it is smaller than the sum of its proper divisors (37550358).

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

21201642 is a wasteful number, since it uses less digits than its factorization.

21201642 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5128 (or 5122 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 21201642 is about 4604.5240796417. The cubic root of 21201642 is about 276.7726459682.

Adding to 21201642 its reverse (24610212), we get a palindrome (45811854).

The spelling of 21201642 in words is "twenty-one million, two hundred one thousand, six hundred forty-two".