21718742 has 4 divisors (see below), whose sum is σ = 32578116. Its totient is φ = 10859370.

The previous prime is 21718721. The next prime is 21718751. The reversal of 21718742 is 24781712.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a junction number, because it is equal to n+sod(n) for n = 21718699 and 21718708.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5429684 + ... + 5429687.

It is an arithmetic number, because the mean of its divisors is an integer number (8144529).

Almost surely, 2^21718742 is an apocalyptic number.

21718742 is a deficient number, since it is larger than the sum of its proper divisors (10859374).

21718742 is a wasteful number, since it uses less digits than its factorization.

21718742 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10859373.

The product of its digits is 6272, while the sum is 32.

The square root of 21718742 is about 4660.3371122699. The cubic root of 21718742 is about 279.0047232235.

The spelling of 21718742 in words is "twenty-one million, seven hundred eighteen thousand, seven hundred forty-two".