21153285 has 16 divisors (see below), whose sum is σ = 37606080. Its totient is φ = 11281680.

The previous prime is 21153281. The next prime is 21153299. The reversal of 21153285 is 58235112.

It is a happy number.

It is not a de Polignac number, because 21153285 - 2² = 21153281 is a prime.

It is a super-2 number, since 2×21153285² = 894922932582450, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21153281) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 78211 + ... + 78480.

It is an arithmetic number, because the mean of its divisors is an integer number (2350380).

Almost surely, 2^21153285 is an apocalyptic number.

It is an amenable number.

21153285 is a deficient number, since it is larger than the sum of its proper divisors (16452795).

21153285 is a wasteful number, since it uses less digits than its factorization.

21153285 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 156705 (or 156699 counting only the distinct ones).

The product of its digits is 2400, while the sum is 27.

The square root of 21153285 is about 4599.2700507798. The cubic root of 21153285 is about 276.5620634868.

Adding to 21153285 its reverse (58235112), we get a palindrome (79388397).

The spelling of 21153285 in words is "twenty-one million, one hundred fifty-three thousand, two hundred eighty-five".