21904071 has 32 divisors (see below), whose sum is σ = 34603008. Its totient is φ = 12065760.

The previous prime is 21904061. The next prime is 21904081. The reversal of 21904071 is 17040912.

It is an interprime number because it is at equal distance from previous prime (21904061) and next prime (21904081).

It is not a de Polignac number, because 21904071 - 2⁷ = 21903943 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21904031) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 114586 + ... + 114776.

It is an arithmetic number, because the mean of its divisors is an integer number (1081344).

Almost surely, 2^21904071 is an apocalyptic number.

21904071 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21904071 is a deficient number, since it is larger than the sum of its proper divisors (12698937).

21904071 is a wasteful number, since it uses less digits than its factorization.

21904071 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 371.

The product of its (nonzero) digits is 504, while the sum is 24.

The square root of 21904071 is about 4680.1785222361. The cubic root of 21904071 is about 279.7960717501.

Adding to 21904071 its reverse (17040912), we get a palindrome (38944983).

The spelling of 21904071 in words is "twenty-one million, nine hundred four thousand, seventy-one".