21029797 has 4 divisors (see below), whose sum is σ = 21944160. Its totient is φ = 20115436.

The previous prime is 21029791. The next prime is 21029831. The reversal of 21029797 is 79792012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21029797 is a prime.

It is a super-3 number, since 3×21029797³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21029791) 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 3 ways as a sum of consecutive naturals, for example, 457147 + ... + 457192.

It is an arithmetic number, because the mean of its divisors is an integer number (5486040).

Almost surely, 2^21029797 is an apocalyptic number.

It is an amenable number.

21029797 is a deficient number, since it is larger than the sum of its proper divisors (914363).

21029797 is an equidigital number, since it uses as much as digits as its factorization.

21029797 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 914362.

The product of its (nonzero) digits is 15876, while the sum is 37.

The square root of 21029797 is about 4585.8256617538. The cubic root of 21029797 is about 276.0228443249.

The spelling of 21029797 in words is "twenty-one million, twenty-nine thousand, seven hundred ninety-seven".