21516011 has 4 divisors (see below), whose sum is σ = 23472024. Its totient is φ = 19560000.

The previous prime is 21515983. The next prime is 21516029. The reversal of 21516011 is 11061512.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21516011 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21516041) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 977990 + ... + 978011.

It is an arithmetic number, because the mean of its divisors is an integer number (5868006).

Almost surely, 2^21516011 is an apocalyptic number.

21516011 is a deficient number, since it is larger than the sum of its proper divisors (1956013).

21516011 is a wasteful number, since it uses less digits than its factorization.

21516011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1956012.

The product of its (nonzero) digits is 60, while the sum is 17.

The square root of 21516011 is about 4638.5354369671. The cubic root of 21516011 is about 278.1338959575.

Adding to 21516011 its reverse (11061512), we get a palindrome (32577523).

The spelling of 21516011 in words is "twenty-one million, five hundred sixteen thousand, eleven".