21288995 has 32 divisors (see below), whose sum is σ = 31933440. Its totient is φ = 13265280.

The previous prime is 21288991. The next prime is 21288997. The reversal of 21288995 is 59988212.

It is a Cunningham number, because it is equal to 4614²-1.

It is not a de Polignac number, because 21288995 - 2² = 21288991 is a prime.

It is a super-2 number, since 2×21288995² = 906442616220050, which contains 22 as substring.

It is a Smith number, since the sum of its digits (44) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (21288991) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 31976 + ... + 32634.

It is an arithmetic number, because the mean of its divisors is an integer number (997920).

Almost surely, 2^21288995 is an apocalyptic number.

21288995 is a deficient number, since it is larger than the sum of its proper divisors (10644445).

21288995 is a wasteful number, since it uses less digits than its factorization.

21288995 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 755.

The product of its digits is 103680, while the sum is 44.

The square root of 21288995 is about 4613.9998916342. Note that the first 3 decimals coincide. The cubic root of 21288995 is about 277.1522359534.

The spelling of 21288995 in words is "twenty-one million, two hundred eighty-eight thousand, nine hundred ninety-five".