20978065 has 8 divisors (see below), whose sum is σ = 25225128. Its totient is φ = 16748160.

The previous prime is 20978021. The next prime is 20978077. The reversal of 20978065 is 56087902.

It can be written as a sum of positive squares in 4 ways, for example, as 2556801 + 18421264 = 1599^2 + 4292^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20978065 - 2¹⁹ = 20453777 is a prime.

It is a super-2 number, since 2×20978065² = 880158422288450, which contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1422 + ... + 6631.

It is an arithmetic number, because the mean of its divisors is an integer number (3153141).

Almost surely, 2^20978065 is an apocalyptic number.

It is an amenable number.

20978065 is a deficient number, since it is larger than the sum of its proper divisors (4247063).

20978065 is an equidigital number, since it uses as much as digits as its factorization.

20978065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8579.

The product of its (nonzero) digits is 30240, while the sum is 37.

The square root of 20978065 is about 4580.1817649521. The cubic root of 20978065 is about 275.7963254404.

The spelling of 20978065 in words is "twenty million, nine hundred seventy-eight thousand, sixty-five".