21188742 has 16 divisors (see below), whose sum is σ = 42422832. Its totient is φ = 7055360.

The previous prime is 21188737. The next prime is 21188747. The reversal of 21188742 is 24788112.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21188737) and next prime (21188747).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21188747) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9142 + ... + 11222.

It is an arithmetic number, because the mean of its divisors is an integer number (2651427).

Almost surely, 2^21188742 is an apocalyptic number.

21188742 is an abundant number, since it is smaller than the sum of its proper divisors (21234090).

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

21188742 is a wasteful number, since it uses less digits than its factorization.

21188742 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3783.

The product of its digits is 7168, while the sum is 33.

The square root of 21188742 is about 4603.1230702644. The cubic root of 21188742 is about 276.7165010794.

The spelling of 21188742 in words is "twenty-one million, one hundred eighty-eight thousand, seven hundred forty-two".