21578678 has 16 divisors (see below), whose sum is σ = 37388304. Its totient is φ = 9231360.

The previous prime is 21578671. The next prime is 21578681. The reversal of 21578678 is 87687512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21578671) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28475 + ... + 29222.

It is an arithmetic number, because the mean of its divisors is an integer number (2336769).

Almost surely, 2^21578678 is an apocalyptic number.

21578678 is a deficient number, since it is larger than the sum of its proper divisors (15809626).

21578678 is a wasteful number, since it uses less digits than its factorization.

21578678 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57727.

The product of its digits is 188160, while the sum is 44.

The square root of 21578678 is about 4645.2855671099. The cubic root of 21578678 is about 278.4036628504.

The spelling of 21578678 in words is "twenty-one million, five hundred seventy-eight thousand, six hundred seventy-eight".