21681774 has 24 divisors (see below), whose sum is σ = 49450440. Its totient is φ = 6846768.

The previous prime is 21681769. The next prime is 21681797. The reversal of 21681774 is 47718612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 31357 + ... + 32040.

It is an arithmetic number, because the mean of its divisors is an integer number (2060435).

Almost surely, 2^21681774 is an apocalyptic number.

21681774 is an abundant number, since it is smaller than the sum of its proper divisors (27768666).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21681774 is a wasteful number, since it uses less digits than its factorization.

21681774 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63424 (or 63421 counting only the distinct ones).

The product of its digits is 18816, while the sum is 36.

The square root of 21681774 is about 4656.3691863941. The cubic root of 21681774 is about 278.8463330769.

The spelling of 21681774 in words is "twenty-one million, six hundred eighty-one thousand, seven hundred seventy-four".