21731594 has 4 divisors (see below), whose sum is σ = 32597394. Its totient is φ = 10865796.

The previous prime is 21731587. The next prime is 21731597. The reversal of 21731594 is 49513712.

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., 18966025 + 2765569 = 4355^2 + 1663^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21731594.

It is not an unprimeable number, because it can be changed into a prime (21731597) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5432897 + ... + 5432900.

Almost surely, 2^21731594 is an apocalyptic number.

21731594 is a deficient number, since it is larger than the sum of its proper divisors (10865800).

21731594 is a wasteful number, since it uses less digits than its factorization.

21731594 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10865799.

The product of its digits is 7560, while the sum is 32.

The square root of 21731594 is about 4661.7157785519. The cubic root of 21731594 is about 279.0597457727.

The spelling of 21731594 in words is "twenty-one million, seven hundred thirty-one thousand, five hundred ninety-four".