21253659 has 8 divisors (see below), whose sum is σ = 32386560. Its totient is φ = 12144936.

The previous prime is 21253657. The next prime is 21253663. The reversal of 21253659 is 95635212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21253659 - 2¹ = 21253657 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21253657) 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 7 ways as a sum of consecutive naturals, for example, 506019 + ... + 506060.

It is an arithmetic number, because the mean of its divisors is an integer number (4048320).

Almost surely, 2^21253659 is an apocalyptic number.

21253659 is a deficient number, since it is larger than the sum of its proper divisors (11132901).

21253659 is a wasteful number, since it uses less digits than its factorization.

21253659 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1012089.

The product of its digits is 16200, while the sum is 33.

The square root of 21253659 is about 4610.1690858362. The cubic root of 21253659 is about 276.9988096583.

It can be divided in two parts, 21253 and 659, that added together give a palindrome (21912).

The spelling of 21253659 in words is "twenty-one million, two hundred fifty-three thousand, six hundred fifty-nine".