21320493 has 4 divisors (see below), whose sum is σ = 28427328. Its totient is φ = 14213660.

The previous prime is 21320491. The next prime is 21320513. The reversal of 21320493 is 39402312.

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 a cyclic number.

It is not a de Polignac number, because 21320493 - 2¹ = 21320491 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21320491) 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, 3553413 + ... + 3553418.

It is an arithmetic number, because the mean of its divisors is an integer number (7106832).

Almost surely, 2^21320493 is an apocalyptic number.

It is an amenable number.

21320493 is a deficient number, since it is larger than the sum of its proper divisors (7106835).

21320493 is an equidigital number, since it uses as much as digits as its factorization.

21320493 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7106834.

The product of its (nonzero) digits is 1296, while the sum is 24.

The square root of 21320493 is about 4617.4119374385. The cubic root of 21320493 is about 277.2888548859.

It can be divided in two parts, 213 and 20493, that added together give a triangular number (20706 = T₂₀₃).

The spelling of 21320493 in words is "twenty-one million, three hundred twenty thousand, four hundred ninety-three".