21351473 has 16 divisors (see below), whose sum is σ = 26562816. Its totient is φ = 16861440.

The previous prime is 21351469. The next prime is 21351503. The reversal of 21351473 is 37415312.

It is a cyclic number.

It is not a de Polignac number, because 21351473 - 2² = 21351469 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21351413) 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, 1961 + ... + 6822.

It is an arithmetic number, because the mean of its divisors is an integer number (1660176).

Almost surely, 2^21351473 is an apocalyptic number.

It is an amenable number.

21351473 is a deficient number, since it is larger than the sum of its proper divisors (5211343).

21351473 is a wasteful number, since it uses less digits than its factorization.

21351473 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8824.

The product of its digits is 2520, while the sum is 26.

The square root of 21351473 is about 4620.7654127861. The cubic root of 21351473 is about 277.4230958606.

Adding to 21351473 its reverse (37415312), we get a palindrome (58766785).

The spelling of 21351473 in words is "twenty-one million, three hundred fifty-one thousand, four hundred seventy-three".