21731671 has 8 divisors (see below), whose sum is σ = 23451120. Its totient is φ = 20019072.

The previous prime is 21731669. The next prime is 21731683. The reversal of 21731671 is 17613712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21731671 - 2¹ = 21731669 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21731621) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6300 + ... + 9118.

It is an arithmetic number, because the mean of its divisors is an integer number (2931390).

Almost surely, 2^21731671 is an apocalyptic number.

21731671 is a deficient number, since it is larger than the sum of its proper divisors (1719449).

21731671 is a wasteful number, since it uses less digits than its factorization.

21731671 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3425.

The product of its digits is 1764, while the sum is 28.

The square root of 21731671 is about 4661.7240373064. The cubic root of 21731671 is about 279.0600753631.

It can be divided in two parts, 2173 and 1671, that added together give a square (3844 = 62²).

The spelling of 21731671 in words is "twenty-one million, seven hundred thirty-one thousand, six hundred seventy-one".