21131672 has 8 divisors (see below), whose sum is σ = 39621900. Its totient is φ = 10565832.

The previous prime is 21131653. The next prime is 21131689. The reversal of 21131672 is 27613112.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1320722 + ... + 1320737.

Almost surely, 2^21131672 is an apocalyptic number.

It is an amenable number.

21131672 is a deficient number, since it is larger than the sum of its proper divisors (18490228).

21131672 is a wasteful number, since it uses less digits than its factorization.

21131672 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2641465 (or 2641461 counting only the distinct ones).

The product of its digits is 504, while the sum is 23.

The square root of 21131672 is about 4596.9198383265. The cubic root of 21131672 is about 276.4678405678.

Adding to 21131672 its reverse (27613112), we get a palindrome (48744784).

The spelling of 21131672 in words is "twenty-one million, one hundred thirty-one thousand, six hundred seventy-two".