21109242 has 32 divisors (see below), whose sum is σ = 52637184. Its totient is φ = 5482800.

The previous prime is 21109241. The next prime is 21109243. The reversal of 21109242 is 24290112.

It is an interprime number because it is at equal distance from previous prime (21109241) and next prime (21109243).

It is a Harshad number since it is a multiple of its sum of digits (21).

It is not an unprimeable number, because it can be changed into a prime (21109241) 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, 22384 + ... + 23307.

It is an arithmetic number, because the mean of its divisors is an integer number (1644912).

Almost surely, 2^21109242 is an apocalyptic number.

21109242 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

21109242 is an abundant number, since it is smaller than the sum of its proper divisors (31527942).

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

21109242 is a wasteful number, since it uses less digits than its factorization.

21109242 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45714.

The product of its (nonzero) digits is 288, while the sum is 21.

The square root of 21109242 is about 4594.4795135031. The cubic root of 21109242 is about 276.3699879382.

Adding to 21109242 its reverse (24290112), we get a palindrome (45399354).

The spelling of 21109242 in words is "twenty-one million, one hundred nine thousand, two hundred forty-two".