21031671 has 16 divisors (see below), whose sum is σ = 29445120. Its totient is φ = 13335360.

The previous prime is 21031667. The next prime is 21031697. The reversal of 21031671 is 17613012.

It is not a de Polignac number, because 21031671 - 2² = 21031667 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21031471) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3571 + ... + 7403.

It is an arithmetic number, because the mean of its divisors is an integer number (1840320).

Almost surely, 2^21031671 is an apocalyptic number.

21031671 is a deficient number, since it is larger than the sum of its proper divisors (8413449).

21031671 is a wasteful number, since it uses less digits than its factorization.

21031671 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3926.

The product of its (nonzero) digits is 252, while the sum is 21.

The square root of 21031671 is about 4586.0299824576. The cubic root of 21031671 is about 276.0310430322.

Adding to 21031671 its reverse (17613012), we get a palindrome (38644683).

The spelling of 21031671 in words is "twenty-one million, thirty-one thousand, six hundred seventy-one".