20787878 has 4 divisors (see below), whose sum is σ = 31181820. Its totient is φ = 10393938.

The previous prime is 20787869. The next prime is 20787901. The reversal of 20787878 is 87878702.

It is a semiprime because it is the product of two primes.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5196968 + ... + 5196971.

It is an arithmetic number, because the mean of its divisors is an integer number (7795455).

Almost surely, 2^20787878 is an apocalyptic number.

20787878 is a deficient number, since it is larger than the sum of its proper divisors (10393942).

20787878 is a wasteful number, since it uses less digits than its factorization.

20787878 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10393941.

The product of its (nonzero) digits is 351232, while the sum is 47.

The square root of 20787878 is about 4559.3725445504. The cubic root of 20787878 is about 274.9603380817.

The spelling of 20787878 in words is "twenty million, seven hundred eighty-seven thousand, eight hundred seventy-eight".