21262729 has 4 divisors (see below), whose sum is σ = 22381840. Its totient is φ = 20143620.

The previous prime is 21262727. The next prime is 21262751. The reversal of 21262729 is 92726212.

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 not a de Polignac number, because 21262729 - 2¹ = 21262727 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21262729.

It is not an unprimeable number, because it can be changed into a prime (21262727) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 559527 + ... + 559564.

It is an arithmetic number, because the mean of its divisors is an integer number (5595460).

Almost surely, 2^21262729 is an apocalyptic number.

It is an amenable number.

21262729 is a deficient number, since it is larger than the sum of its proper divisors (1119111).

21262729 is a wasteful number, since it uses less digits than its factorization.

21262729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1119110.

The product of its digits is 6048, while the sum is 31.

The square root of 21262729 is about 4611.1526758502. The cubic root of 21262729 is about 277.0382071397.

The spelling of 21262729 in words is "twenty-one million, two hundred sixty-two thousand, seven hundred twenty-nine".