21682778 has 32 divisors (see below), whose sum is σ = 36666000. Its totient is φ = 9547776.

The previous prime is 21682757. The next prime is 21682823. The reversal of 21682778 is 87728612.

It can be written as a sum of positive squares in 8 ways, for example, as 1315609 + 20367169 = 1147^2 + 4513^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 112250 + ... + 112442.

Almost surely, 2^21682778 is an apocalyptic number.

21682778 is a deficient number, since it is larger than the sum of its proper divisors (14983222).

21682778 is a wasteful number, since it uses less digits than its factorization.

21682778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 386.

The product of its digits is 75264, while the sum is 41.

The square root of 21682778 is about 4656.4769944670. The cubic root of 21682778 is about 278.8506371127.

The spelling of 21682778 in words is "twenty-one million, six hundred eighty-two thousand, seven hundred seventy-eight".