21033729 has 16 divisors (see below), whose sum is σ = 32236800. Its totient is φ = 13538448.

The previous prime is 21033721. The next prime is 21033737. The reversal of 21033729 is 92733012.

It is an interprime number because it is at equal distance from previous prime (21033721) and next prime (21033737).

It is not a de Polignac number, because 21033729 - 2³ = 21033721 is a prime.

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 (21033721) 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, 12649 + ... + 14214.

It is an arithmetic number, because the mean of its divisors is an integer number (2014800).

Almost surely, 2^21033729 is an apocalyptic number.

21033729 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

It is an amenable number.

21033729 is a deficient number, since it is larger than the sum of its proper divisors (11203071).

21033729 is a wasteful number, since it uses less digits than its factorization.

21033729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26901 (or 26895 counting only the distinct ones).

The product of its (nonzero) digits is 2268, while the sum is 27.

The square root of 21033729 is about 4586.2543540454. The cubic root of 21033729 is about 276.0400461741.

It can be divided in two parts, 2103 and 3729, that added together give a cube (5832 = 18³).

The spelling of 21033729 in words is "twenty-one million, thirty-three thousand, seven hundred twenty-nine".