21428493 has 8 divisors (see below), whose sum is σ = 28963008. Its totient is φ = 14089824.

The previous prime is 21428489. The next prime is 21428497. The reversal of 21428493 is 39482412.

It is an interprime number because it is at equal distance from previous prime (21428489) and next prime (21428497).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21428493 - 2² = 21428489 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 (21428497) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 48705 + ... + 49142.

It is an arithmetic number, because the mean of its divisors is an integer number (3620376).

Almost surely, 2^21428493 is an apocalyptic number.

It is an amenable number.

21428493 is a deficient number, since it is larger than the sum of its proper divisors (7534515).

21428493 is an equidigital number, since it uses as much as digits as its factorization.

21428493 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 97923.

The product of its digits is 13824, while the sum is 33.

The square root of 21428493 is about 4629.0920276011. The cubic root of 21428493 is about 277.7562732804.

The spelling of 21428493 in words is "twenty-one million, four hundred twenty-eight thousand, four hundred ninety-three".