21465791 has 4 divisors (see below), whose sum is σ = 21629784. Its totient is φ = 21301800.

The previous prime is 21465779. The next prime is 21465799. The reversal of 21465791 is 19756412.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21465791 - 2⁶ = 21465727 is a prime.

It is a super-3 number, since 3×21465791³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a plaindrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21465799) 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, 81800 + ... + 82061.

It is an arithmetic number, because the mean of its divisors is an integer number (5407446).

Almost surely, 2^21465791 is an apocalyptic number.

21465791 is a deficient number, since it is larger than the sum of its proper divisors (163993).

21465791 is a wasteful number, since it uses less digits than its factorization.

21465791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 163992.

The product of its digits is 15120, while the sum is 35.

The square root of 21465791 is about 4633.1189278930. The cubic root of 21465791 is about 277.9173321819.

The spelling of 21465791 in words is "twenty-one million, four hundred sixty-five thousand, seven hundred ninety-one".