21475729 has 4 divisors (see below), whose sum is σ = 23428080. Its totient is φ = 19523380.

The previous prime is 21475723. The next prime is 21475733. The reversal of 21475729 is 92757412.

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 21475729 - 2⁵ = 21475697 is a prime.

It is a super-2 number, since 2×21475729² = 922413872162882, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21475723) 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, 976159 + ... + 976180.

It is an arithmetic number, because the mean of its divisors is an integer number (5857020).

Almost surely, 2^21475729 is an apocalyptic number.

It is an amenable number.

21475729 is a deficient number, since it is larger than the sum of its proper divisors (1952351).

21475729 is a wasteful number, since it uses less digits than its factorization.

21475729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1952350.

The product of its digits is 35280, while the sum is 37.

The square root of 21475729 is about 4634.1912994610. The cubic root of 21475729 is about 277.9602146194.

The spelling of 21475729 in words is "twenty-one million, four hundred seventy-five thousand, seven hundred twenty-nine".