20278861 has 4 divisors (see below), whose sum is σ = 20320000. Its totient is φ = 20237724.

The previous prime is 20278837. The next prime is 20278879. The reversal of 20278861 is 16887202.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20278861 - 2¹⁷ = 20147789 is a prime.

It is a super-2 number, since 2×20278861² = 822464406914642, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20278261) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19821 + ... + 20818.

It is an arithmetic number, because the mean of its divisors is an integer number (5080000).

Almost surely, 2^20278861 is an apocalyptic number.

It is an amenable number.

20278861 is a deficient number, since it is larger than the sum of its proper divisors (41139).

20278861 is an equidigital number, since it uses as much as digits as its factorization.

20278861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41138.

The product of its (nonzero) digits is 10752, while the sum is 34.

The square root of 20278861 is about 4503.2056359887. The cubic root of 20278861 is about 272.6975186092.

The spelling of 20278861 in words is "twenty million, two hundred seventy-eight thousand, eight hundred sixty-one".