21678722 has 16 divisors (see below), whose sum is σ = 35185920. Its totient is φ = 9958032.

The previous prime is 21678697. The next prime is 21678731. The reversal of 21678722 is 22787612.

It is a Smith number, since the sum of its digits (35) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3929 + ... + 7667.

It is an arithmetic number, because the mean of its divisors is an integer number (2199120).

Almost surely, 2^21678722 is an apocalyptic number.

21678722 is a deficient number, since it is larger than the sum of its proper divisors (13507198).

21678722 is a wasteful number, since it uses less digits than its factorization.

21678722 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3977.

The product of its digits is 18816, while the sum is 35.

The square root of 21678722 is about 4656.0414517055. The cubic root of 21678722 is about 278.8332486779.

The spelling of 21678722 in words is "twenty-one million, six hundred seventy-eight thousand, seven hundred twenty-two".