21861039 has 8 divisors (see below), whose sum is σ = 30682240. Its totient is φ = 13806936.

The previous prime is 21861019. The next prime is 21861053. The reversal of 21861039 is 93016812.

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

It is not a de Polignac number, because 21861039 - 2¹⁶ = 21795503 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21860997 and 21861015.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21861019) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 191707 + ... + 191820.

It is an arithmetic number, because the mean of its divisors is an integer number (3835280).

Almost surely, 2^21861039 is an apocalyptic number.

21861039 is a deficient number, since it is larger than the sum of its proper divisors (8821201).

21861039 is a wasteful number, since it uses less digits than its factorization.

21861039 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 383549.

The product of its (nonzero) digits is 2592, while the sum is 30.

The square root of 21861039 is about 4675.5790015783. The cubic root of 21861039 is about 279.6127256535.

The spelling of 21861039 in words is "twenty-one million, eight hundred sixty-one thousand, thirty-nine".