20978316 has 18 divisors (see below), whose sum is σ = 53028612. Its totient is φ = 6992760.

The previous prime is 20978311. The next prime is 20978317. The reversal of 20978316 is 61387902.

It is a tau number, because it is divible by the number of its divisors (18).

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 582731 = 20978316 / (2 + 0 + 9 + 7 + 8 + 3 + 1 + 6).

It is not an unprimeable number, because it can be changed into a prime (20978311) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 291330 + ... + 291401.

It is an arithmetic number, because the mean of its divisors is an integer number (2946034).

Almost surely, 2^20978316 is an apocalyptic number.

It is an amenable number.

20978316 is an abundant number, since it is smaller than the sum of its proper divisors (32050296).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20978316 is a wasteful number, since it uses less digits than its factorization.

20978316 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 582741 (or 582736 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 36.

The square root of 20978316 is about 4580.2091655295. The cubic root of 20978316 is about 275.7974253926.

The spelling of 20978316 in words is "twenty million, nine hundred seventy-eight thousand, three hundred sixteen".