21021471 has 16 divisors (see below), whose sum is σ = 32497920. Its totient is φ = 13404600.

The previous prime is 21021463. The next prime is 21021499. The reversal of 21021471 is 17412012.

It is not a de Polignac number, because 21021471 - 2³ = 21021463 is a prime.

It is a super-3 number, since 3×21021471³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21021431) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16305 + ... + 17546.

It is an arithmetic number, because the mean of its divisors is an integer number (2031120).

Almost surely, 2^21021471 is an apocalyptic number.

21021471 is a deficient number, since it is larger than the sum of its proper divisors (11476449).

21021471 is a wasteful number, since it uses less digits than its factorization.

21021471 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33883 (or 33877 counting only the distinct ones).

The product of its (nonzero) digits is 112, while the sum is 18.

The square root of 21021471 is about 4584.9177746171. The cubic root of 21021471 is about 275.9864123746.

Adding to 21021471 its reverse (17412012), we get a palindrome (38433483).

The spelling of 21021471 in words is "twenty-one million, twenty-one thousand, four hundred seventy-one".