21157275 has 12 divisors (see below), whose sum is σ = 34980152. Its totient is φ = 11283840.

The previous prime is 21157273. The next prime is 21157277. The reversal of 21157275 is 57275112.

It is an interprime number because it is at equal distance from previous prime (21157273) and next prime (21157277).

It is not a de Polignac number, because 21157275 - 2¹ = 21157273 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21157273) 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 11 ways as a sum of consecutive naturals, for example, 140974 + ... + 141123.

Almost surely, 2^21157275 is an apocalyptic number.

21157275 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21157275 is a deficient number, since it is larger than the sum of its proper divisors (13822877).

21157275 is a wasteful number, since it uses less digits than its factorization.

21157275 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 282110 (or 282105 counting only the distinct ones).

The product of its digits is 4900, while the sum is 30.

The square root of 21157275 is about 4599.7037948111. The cubic root of 21157275 is about 276.5794510661.

The spelling of 21157275 in words is "twenty-one million, one hundred fifty-seven thousand, two hundred seventy-five".