20878415 has 4 divisors (see below), whose sum is σ = 25054104. Its totient is φ = 16702728.

The previous prime is 20878399. The next prime is 20878433. The reversal of 20878415 is 51487802.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 51487802 = 2 ⋅25743901.

It is a cyclic number.

It is not a de Polignac number, because 20878415 - 2⁴ = 20878399 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2087837 + ... + 2087846.

It is an arithmetic number, because the mean of its divisors is an integer number (6263526).

Almost surely, 2^20878415 is an apocalyptic number.

20878415 is a deficient number, since it is larger than the sum of its proper divisors (4175689).

20878415 is an equidigital number, since it uses as much as digits as its factorization.

20878415 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4175688.

The product of its (nonzero) digits is 17920, while the sum is 35.

The square root of 20878415 is about 4569.2904263135. The cubic root of 20878415 is about 275.3589362631.

The spelling of 20878415 in words is "twenty million, eight hundred seventy-eight thousand, four hundred fifteen".