21274387 has 4 divisors (see below), whose sum is σ = 21320800. Its totient is φ = 21227976.

The previous prime is 21274373. The next prime is 21274391. The reversal of 21274387 is 78347212.

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

It is a cyclic number.

It is not a de Polignac number, because 21274387 - 2¹⁹ = 20750099 is a prime.

It is a super-3 number, since 3×21274387³ (a number of 23 digits) contains 333 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21274307) 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, 22512 + ... + 23437.

It is an arithmetic number, because the mean of its divisors is an integer number (5330200).

Almost surely, 2^21274387 is an apocalyptic number.

21274387 is a deficient number, since it is larger than the sum of its proper divisors (46413).

21274387 is an equidigital number, since it uses as much as digits as its factorization.

21274387 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46412.

The product of its digits is 18816, while the sum is 34.

The square root of 21274387 is about 4612.4166117123. The cubic root of 21274387 is about 277.0888296998.

The spelling of 21274387 in words is "twenty-one million, two hundred seventy-four thousand, three hundred eighty-seven".