21712238 has 4 divisors (see below), whose sum is σ = 32568360. Its totient is φ = 10856118.

The previous prime is 21712237. The next prime is 21712241. The reversal of 21712238 is 83221712.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21712237) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5428058 + ... + 5428061.

It is an arithmetic number, because the mean of its divisors is an integer number (8142090).

Almost surely, 2^21712238 is an apocalyptic number.

21712238 is a deficient number, since it is larger than the sum of its proper divisors (10856122).

21712238 is a wasteful number, since it uses less digits than its factorization.

21712238 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10856121.

The product of its digits is 1344, while the sum is 26.

The square root of 21712238 is about 4659.6392564232. The cubic root of 21712238 is about 278.9768697396.

The spelling of 21712238 in words is "twenty-one million, seven hundred twelve thousand, two hundred thirty-eight".