21971123 has 4 divisors (see below), whose sum is σ = 23263560. Its totient is φ = 20678688.

The previous prime is 21971119. The next prime is 21971129. The reversal of 21971123 is 32117912.

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 21971123 - 2² = 21971119 is a prime.

It is a super-2 number, since 2×21971123² = 965460491762258, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21971092 and 21971101.

It is not an unprimeable number, because it can be changed into a prime (21971129) 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, 646193 + ... + 646226.

It is an arithmetic number, because the mean of its divisors is an integer number (5815890).

Almost surely, 2^21971123 is an apocalyptic number.

21971123 is a deficient number, since it is larger than the sum of its proper divisors (1292437).

21971123 is a wasteful number, since it uses less digits than its factorization.

21971123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1292436.

The product of its digits is 756, while the sum is 26.

The square root of 21971123 is about 4687.3364504802. The cubic root of 21971123 is about 280.0812816744.

The spelling of 21971123 in words is "twenty-one million, nine hundred seventy-one thousand, one hundred twenty-three".