21152473 has 4 divisors (see below), whose sum is σ = 21190608. Its totient is φ = 21114340.

The previous prime is 21152449. The next prime is 21152477. The reversal of 21152473 is 37425112.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21152473 - 2⁵ = 21152441 is a prime.

It is a super-2 number, since 2×21152473² = 894854228031458, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21152477) 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 3 ways as a sum of consecutive naturals, for example, 18223 + ... + 19348.

It is an arithmetic number, because the mean of its divisors is an integer number (5297652).

Almost surely, 2^21152473 is an apocalyptic number.

It is an amenable number.

21152473 is a deficient number, since it is larger than the sum of its proper divisors (38135).

21152473 is an equidigital number, since it uses as much as digits as its factorization.

21152473 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38134.

The product of its digits is 1680, while the sum is 25.

The square root of 21152473 is about 4599.1817750552. The cubic root of 21152473 is about 276.5585246942.

Adding to 21152473 its reverse (37425112), we get a palindrome (58577585).

The spelling of 21152473 in words is "twenty-one million, one hundred fifty-two thousand, four hundred seventy-three".