21563742 has 16 divisors (see below), whose sum is σ = 45002880. Its totient is φ = 6875352.

The previous prime is 21563723. The next prime is 21563753. The reversal of 21563742 is 24736512.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 77992 + ... + 78267.

It is an arithmetic number, because the mean of its divisors is an integer number (2812680).

Almost surely, 2^21563742 is an apocalyptic number.

21563742 is an abundant number, since it is smaller than the sum of its proper divisors (23439138).

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

21563742 is a wasteful number, since it uses less digits than its factorization.

21563742 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 156287.

The product of its digits is 10080, while the sum is 30.

The square root of 21563742 is about 4643.6776373904. The cubic root of 21563742 is about 278.3394142918.

The spelling of 21563742 in words is "twenty-one million, five hundred sixty-three thousand, seven hundred forty-two".