21682161 has 12 divisors (see below), whose sum is σ = 32478992. Its totient is φ = 14454612.

The previous prime is 21682151. The next prime is 21682163. The reversal of 21682161 is 16128612.

It is not a de Polignac number, because 21682161 - 2¹³ = 21673969 is a prime.

It is a super-2 number, since 2×21682161² = 940232211259842, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21682163) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 44371 + ... + 44856.

Almost surely, 2^21682161 is an apocalyptic number.

It is an amenable number.

21682161 is a deficient number, since it is larger than the sum of its proper divisors (10796831).

21682161 is an frugal number, since it uses more digits than its factorization.

21682161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 89242 (or 89230 counting only the distinct ones).

The product of its digits is 1152, while the sum is 27.

The square root of 21682161 is about 4656.4107421919. The cubic root of 21682161 is about 278.8479921184.

The spelling of 21682161 in words is "twenty-one million, six hundred eighty-two thousand, one hundred sixty-one".