20687816 has 16 divisors (see below), whose sum is σ = 39692400. Its totient is φ = 10103184.

The previous prime is 20687803. The next prime is 20687839. The reversal of 20687816 is 61878602.

It is a self number, because there is not a number n which added to its sum of digits gives 20687816.

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, 29726 + ... + 30413.

It is an arithmetic number, because the mean of its divisors is an integer number (2480775).

Almost surely, 2^20687816 is an apocalyptic number.

It is an amenable number.

20687816 is a deficient number, since it is larger than the sum of its proper divisors (19004584).

20687816 is a wasteful number, since it uses less digits than its factorization.

20687816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60188 (or 60184 counting only the distinct ones).

The product of its (nonzero) digits is 32256, while the sum is 38.

The square root of 20687816 is about 4548.3860873941. The cubic root of 20687816 is about 274.5184564505.

The spelling of 20687816 in words is "twenty million, six hundred eighty-seven thousand, eight hundred sixteen".