20977864 has 32 divisors (see below), whose sum is σ = 42237720. Its totient is φ = 9732096.

The previous prime is 20977861. The next prime is 20977871. The reversal of 20977864 is 46877902.

It can be written as a sum of positive squares in 4 ways, for example, as 14516100 + 6461764 = 3810^2 + 2542^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 20977864.

It is not an unprimeable number, because it can be changed into a prime (20977861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8872 + ... + 10984.

Almost surely, 2^20977864 is an apocalyptic number.

It is an amenable number.

20977864 is an abundant number, since it is smaller than the sum of its proper divisors (21259856).

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

20977864 is a wasteful number, since it uses less digits than its factorization.

20977864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2209 (or 2205 counting only the distinct ones).

The product of its (nonzero) digits is 169344, while the sum is 43.

The square root of 20977864 is about 4580.1598225389. The cubic root of 20977864 is about 275.7954445960.

The spelling of 20977864 in words is "twenty million, nine hundred seventy-seven thousand, eight hundred sixty-four".