21115633 has 16 divisors (see below), whose sum is σ = 27472896. Its totient is φ = 15737040.

The previous prime is 21115603. The next prime is 21115651. The reversal of 21115633 is 33651112.

It is a happy number.

It is a de Polignac number, because none of the positive numbers 2^k-21115633 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21115603) 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 15 ways as a sum of consecutive naturals, for example, 4191 + ... + 7732.

It is an arithmetic number, because the mean of its divisors is an integer number (1717056).

Almost surely, 2^21115633 is an apocalyptic number.

21115633 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

21115633 is a deficient number, since it is larger than the sum of its proper divisors (6357263).

21115633 is a wasteful number, since it uses less digits than its factorization.

21115633 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11964.

The product of its digits is 540, while the sum is 22.

The square root of 21115633 is about 4595.1749694653. The cubic root of 21115633 is about 276.3978762343.

Adding to 21115633 its reverse (33651112), we get a palindrome (54766745).

It can be divided in two parts, 2111 and 5633, that added together give a square (7744 = 88²).

The spelling of 21115633 in words is "twenty-one million, one hundred fifteen thousand, six hundred thirty-three".