21551379 has 8 divisors (see below), whose sum is σ = 29726160. Its totient is φ = 13872096.

The previous prime is 21551357. The next prime is 21551401. The reversal of 21551379 is 97315512.

It is an interprime number because it is at equal distance from previous prime (21551357) and next prime (21551401).

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

It is not a de Polignac number, because 21551379 - 2⁷ = 21551251 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21553379) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 123772 + ... + 123945.

It is an arithmetic number, because the mean of its divisors is an integer number (3715770).

Almost surely, 2^21551379 is an apocalyptic number.

21551379 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

21551379 is a deficient number, since it is larger than the sum of its proper divisors (8174781).

21551379 is a wasteful number, since it uses less digits than its factorization.

21551379 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 247749.

The product of its digits is 9450, while the sum is 33.

The square root of 21551379 is about 4642.3462817847. The cubic root of 21551379 is about 278.2862112807.

The spelling of 21551379 in words is "twenty-one million, five hundred fifty-one thousand, three hundred seventy-nine".