21660742 has 4 divisors (see below), whose sum is σ = 32491116. Its totient is φ = 10830370.

The previous prime is 21660713. The next prime is 21660757. The reversal of 21660742 is 24706612.

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

It is a self number, because there is not a number n which added to its sum of digits gives 21660742.

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, 5415184 + ... + 5415187.

It is an arithmetic number, because the mean of its divisors is an integer number (8122779).

Almost surely, 2^21660742 is an apocalyptic number.

21660742 is a deficient number, since it is larger than the sum of its proper divisors (10830374).

21660742 is a wasteful number, since it uses less digits than its factorization.

21660742 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10830373.

The product of its (nonzero) digits is 4032, while the sum is 28.

The square root of 21660742 is about 4654.1102264558. The cubic root of 21660742 is about 278.7561406813.

The spelling of 21660742 in words is "twenty-one million, six hundred sixty thousand, seven hundred forty-two".