21005672 has 32 divisors (see below), whose sum is σ = 40629600. Its totient is φ = 10175424.

The previous prime is 21005669. The next prime is 21005681. The reversal of 21005672 is 27650012.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 77954 + ... + 78222.

It is an arithmetic number, because the mean of its divisors is an integer number (1269675).

Almost surely, 2^21005672 is an apocalyptic number.

It is an amenable number.

21005672 is a deficient number, since it is larger than the sum of its proper divisors (19623928).

21005672 is a wasteful number, since it uses less digits than its factorization.

21005672 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 545 (or 541 counting only the distinct ones).

The product of its (nonzero) digits is 840, while the sum is 23.

The square root of 21005672 is about 4583.1945191100. The cubic root of 21005672 is about 275.9172544782.

Adding to 21005672 its reverse (27650012), we get a palindrome (48655684).

The spelling of 21005672 in words is "twenty-one million, five thousand, six hundred seventy-two".