21930071 has 4 divisors (see below), whose sum is σ = 21939600. Its totient is φ = 21920544.

The previous prime is 21929993. The next prime is 21930101. The reversal of 21930071 is 17003912.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21930071 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21930371) 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, 1070 + ... + 6708.

It is an arithmetic number, because the mean of its divisors is an integer number (5484900).

Almost surely, 2^21930071 is an apocalyptic number.

21930071 is a deficient number, since it is larger than the sum of its proper divisors (9529).

21930071 is an equidigital number, since it uses as much as digits as its factorization.

21930071 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9528.

The product of its (nonzero) digits is 378, while the sum is 23.

The square root of 21930071 is about 4682.9553702763. The cubic root of 21930071 is about 279.9067333926.

Adding to 21930071 its reverse (17003912), we get a palindrome (38933983).

The spelling of 21930071 in words is "twenty-one million, nine hundred thirty thousand, seventy-one".