21663742 has 8 divisors (see below), whose sum is σ = 32515632. Its totient is φ = 10825200.

The previous prime is 21663721. The next prime is 21663751. The reversal of 21663742 is 24736612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3642 + ... + 7522.

It is an arithmetic number, because the mean of its divisors is an integer number (4064454).

Almost surely, 2^21663742 is an apocalyptic number.

21663742 is a deficient number, since it is larger than the sum of its proper divisors (10851890).

21663742 is a wasteful number, since it uses less digits than its factorization.

21663742 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6674.

The product of its digits is 12096, while the sum is 31.

The square root of 21663742 is about 4654.4325110587. The cubic root of 21663742 is about 278.7690092743.

The spelling of 21663742 in words is "twenty-one million, six hundred sixty-three thousand, seven hundred forty-two".