21723458 has 4 divisors (see below), whose sum is σ = 32585190. Its totient is φ = 10861728.

The previous prime is 21723451. The next prime is 21723463. The reversal of 21723458 is 85432712.

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

It can be written as a sum of positive squares in only one way, i.e., 14341369 + 7382089 = 3787^2 + 2717^2 .

It is not an unprimeable number, because it can be changed into a prime (21723451) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5430863 + ... + 5430866.

Almost surely, 2^21723458 is an apocalyptic number.

21723458 is a deficient number, since it is larger than the sum of its proper divisors (10861732).

21723458 is a wasteful number, since it uses less digits than its factorization.

21723458 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10861731.

The product of its digits is 13440, while the sum is 32.

The square root of 21723458 is about 4660.8430567870. The cubic root of 21723458 is about 279.0249160912.

The spelling of 21723458 in words is "twenty-one million, seven hundred twenty-three thousand, four hundred fifty-eight".