21661682 has 16 divisors (see below), whose sum is σ = 37315392. Its totient is φ = 9238320.

The previous prime is 21661681. The next prime is 21661693. The reversal of 21661682 is 28616612.

It is a super-4 number, since 4×21661682⁴ (a number of 30 digits) contains 4444 as substring.

It is not an unprimeable number, because it can be changed into a prime (21661681) by changing a digit.

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, 713 + ... + 6620.

It is an arithmetic number, because the mean of its divisors is an integer number (2332212).

Almost surely, 2^21661682 is an apocalyptic number.

21661682 is a deficient number, since it is larger than the sum of its proper divisors (15653710).

21661682 is a wasteful number, since it uses less digits than its factorization.

21661682 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7553.

The product of its digits is 6912, while the sum is 32.

The square root of 21661682 is about 4654.2112113655. The cubic root of 21661682 is about 278.7601729682.

The spelling of 21661682 in words is "twenty-one million, six hundred sixty-one thousand, six hundred eighty-two".