20978836 has 6 divisors (see below), whose sum is σ = 36712970. Its totient is φ = 10489416.

The previous prime is 20978819. The next prime is 20978843. The reversal of 20978836 is 63887902.

It can be written as a sum of positive squares in only one way, i.e., 20611600 + 367236 = 4540^2 + 606^2 .

It is a super-2 number, since 2×20978836² = 880223119829792, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 20978792 and 20978801.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2622351 + ... + 2622358.

Almost surely, 2^20978836 is an apocalyptic number.

It is an amenable number.

20978836 is a deficient number, since it is larger than the sum of its proper divisors (15734134).

20978836 is a wasteful number, since it uses less digits than its factorization.

20978836 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5244713 (or 5244711 counting only the distinct ones).

The product of its (nonzero) digits is 145152, while the sum is 43.

The square root of 20978836 is about 4580.2659311442. The cubic root of 20978836 is about 275.7997041499.

The spelling of 20978836 in words is "twenty million, nine hundred seventy-eight thousand, eight hundred thirty-six".