21861413 has 8 divisors (see below), whose sum is σ = 25660032. Its totient is φ = 18231696.

The previous prime is 21861409. The next prime is 21861443. The reversal of 21861413 is 31416812.

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

It is not a de Polignac number, because 21861413 - 2² = 21861409 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21861443) 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, 41945 + ... + 42462.

It is an arithmetic number, because the mean of its divisors is an integer number (3207504).

Almost surely, 2^21861413 is an apocalyptic number.

It is an amenable number.

21861413 is a deficient number, since it is larger than the sum of its proper divisors (3798619).

21861413 is an equidigital number, since it uses as much as digits as its factorization.

21861413 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84451.

The product of its digits is 1152, while the sum is 26.

The square root of 21861413 is about 4675.6189964538. The cubic root of 21861413 is about 279.6143201883.

The spelling of 21861413 in words is "twenty-one million, eight hundred sixty-one thousand, four hundred thirteen".