21682493 has 4 divisors (see below), whose sum is σ = 24780000. Its totient is φ = 18584988.

The previous prime is 21682487. The next prime is 21682499. The reversal of 21682493 is 39428612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (21682487) and next prime (21682499).

It is a cyclic number.

It is not a de Polignac number, because 21682493 - 2¹⁰ = 21681469 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21682499) 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, 1548743 + ... + 1548756.

It is an arithmetic number, because the mean of its divisors is an integer number (6195000).

Almost surely, 2^21682493 is an apocalyptic number.

It is an amenable number.

21682493 is a deficient number, since it is larger than the sum of its proper divisors (3097507).

21682493 is an equidigital number, since it uses as much as digits as its factorization.

21682493 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3097506.

The product of its digits is 20736, while the sum is 35.

The square root of 21682493 is about 4656.4463918314. The cubic root of 21682493 is about 278.8494153631.

The spelling of 21682493 in words is "twenty-one million, six hundred eighty-two thousand, four hundred ninety-three".