21288029 has 16 divisors (see below), whose sum is σ = 25891200. Its totient is φ = 17145792.

The previous prime is 21288023. The next prime is 21288031. The reversal of 21288029 is 92088212.

It is not a de Polignac number, because 21288029 - 2⁴ = 21288013 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21287986 and 21288004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21288023) 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, 34082 + ... + 34700.

It is an arithmetic number, because the mean of its divisors is an integer number (1618200).

Almost surely, 2^21288029 is an apocalyptic number.

It is an amenable number.

21288029 is a deficient number, since it is larger than the sum of its proper divisors (4603171).

21288029 is an frugal number, since it uses more digits than its factorization.

21288029 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 677 (or 643 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 32.

The square root of 21288029 is about 4613.8952090398. The cubic root of 21288029 is about 277.1480439109.

The spelling of 21288029 in words is "twenty-one million, two hundred eighty-eight thousand, twenty-nine".