27878921 has 16 divisors (see below), whose sum is σ = 34028544. Its totient is φ = 22320144.

The previous prime is 27878911. The next prime is 27878923. The reversal of 27878921 is 12987872.

It is a de Polignac number, because none of the positive numbers 2^k-27878921 is a prime.

It is a super-2 number, since 2×27878921² = 1554468472248482, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (27878923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4910 + ... + 8936.

It is an arithmetic number, because the mean of its divisors is an integer number (2126784).

Almost surely, 2^27878921 is an apocalyptic number.

It is an amenable number.

27878921 is a deficient number, since it is larger than the sum of its proper divisors (6149623).

27878921 is a wasteful number, since it uses less digits than its factorization.

27878921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4100.

The product of its digits is 112896, while the sum is 44.

The square root of 27878921 is about 5280.0493368907. The cubic root of 27878921 is about 303.2205657655.

The spelling of 27878921 in words is "twenty-seven million, eight hundred seventy-eight thousand, nine hundred twenty-one".