21721322 has 16 divisors (see below), whose sum is σ = 37869120. Its totient is φ = 9151008.

The previous prime is 21721303. The next prime is 21721373. The reversal of 21721322 is 22312712.

It is a junction number, because it is equal to n+sod(n) for n = 21721294 and 21721303.

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 7 ways as a sum of consecutive naturals, for example, 12323 + ... + 13974.

It is an arithmetic number, because the mean of its divisors is an integer number (2366820).

Almost surely, 2^21721322 is an apocalyptic number.

21721322 is a deficient number, since it is larger than the sum of its proper divisors (16147798).

21721322 is a wasteful number, since it uses less digits than its factorization.

21721322 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26365.

The product of its digits is 336, while the sum is 20.

The square root of 21721322 is about 4660.6139080598. The cubic root of 21721322 is about 279.0157705743.

It can be divided in two parts, 217213 and 22, that multiplied together give a triangular number (4778686 = T₃₀₉₁).

The spelling of 21721322 in words is "twenty-one million, seven hundred twenty-one thousand, three hundred twenty-two".