21481379 has 4 divisors (see below), whose sum is σ = 22415376. Its totient is φ = 20547384.

The previous prime is 21481337. The next prime is 21481399. The reversal of 21481379 is 97318412.

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 21481379 - 2¹² = 21477283 is a prime.

It is a super-2 number, since 2×21481379² = 922899287483282, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21481309) 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, 466964 + ... + 467009.

It is an arithmetic number, because the mean of its divisors is an integer number (5603844).

Almost surely, 2^21481379 is an apocalyptic number.

21481379 is a deficient number, since it is larger than the sum of its proper divisors (933997).

21481379 is an equidigital number, since it uses as much as digits as its factorization.

21481379 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 933996.

The product of its digits is 12096, while the sum is 35.

The square root of 21481379 is about 4634.8008587209. The cubic root of 21481379 is about 277.9845884526.

The spelling of 21481379 in words is "twenty-one million, four hundred eighty-one thousand, three hundred seventy-nine".