21447375 has 16 divisors (see below), whose sum is σ = 35689056. Its totient is φ = 11438400.

The previous prime is 21447373. The next prime is 21447397. The reversal of 21447375 is 57374412.

It is not a de Polignac number, because 21447375 - 2¹ = 21447373 is a prime.

It is a hoax number, since the sum of its digits (33) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21447373) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 28222 + ... + 28971.

It is an arithmetic number, because the mean of its divisors is an integer number (2230566).

Almost surely, 2^21447375 is an apocalyptic number.

21447375 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21447375 is a deficient number, since it is larger than the sum of its proper divisors (14241681).

21447375 is an equidigital number, since it uses as much as digits as its factorization.

21447375 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57211 (or 57201 counting only the distinct ones).

The product of its digits is 23520, while the sum is 33.

The square root of 21447375 is about 4631.1310713475. The cubic root of 21447375 is about 277.8378322007.

The spelling of 21447375 in words is "twenty-one million, four hundred forty-seven thousand, three hundred seventy-five".