20778015 has 16 divisors (see below), whose sum is σ = 33312096. Its totient is φ = 11059200.

The previous prime is 20778011. The next prime is 20778019. The reversal of 20778015 is 51087702.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (20778011) and next prime (20778019).

It is not a de Polignac number, because 20778015 - 2² = 20778011 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20778011) by changing a digit.

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 in 15 ways as a sum of consecutive naturals, for example, 8535 + ... + 10695.

It is an arithmetic number, because the mean of its divisors is an integer number (2082006).

Almost surely, 2^20778015 is an apocalyptic number.

20778015 is a deficient number, since it is larger than the sum of its proper divisors (12534081).

20778015 is a wasteful number, since it uses less digits than its factorization.

20778015 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2810.

The product of its (nonzero) digits is 3920, while the sum is 30.

The square root of 20778015 is about 4558.2907980953. The cubic root of 20778015 is about 274.9168453816.

The spelling of 20778015 in words is "twenty million, seven hundred seventy-eight thousand, fifteen".