21316738 has 4 divisors (see below), whose sum is σ = 31975110. Its totient is φ = 10658368.

The previous prime is 21316723. The next prime is 21316739. The reversal of 21316738 is 83761312.

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

It can be written as a sum of positive squares in only one way, i.e., 21316689 + 49 = 4617^2 + 7^2 .

It is not an unprimeable number, because it can be changed into a prime (21316739) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5329183 + ... + 5329186.

Almost surely, 2^21316738 is an apocalyptic number.

21316738 is a deficient number, since it is larger than the sum of its proper divisors (10658372).

21316738 is a wasteful number, since it uses less digits than its factorization.

21316738 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10658371.

The product of its digits is 6048, while the sum is 31.

The square root of 21316738 is about 4617.0053064730. The cubic root of 21316738 is about 277.2725750750.

The spelling of 21316738 in words is "twenty-one million, three hundred sixteen thousand, seven hundred thirty-eight".