21861007 has 12 divisors (see below), whose sum is σ = 25506360. Its totient is φ = 18681936.

The previous prime is 21860977. The next prime is 21861013. The reversal of 21861007 is 70016812.

It is not a de Polignac number, because 21861007 - 2¹⁵ = 21828239 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 (21861067) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 31953 + ... + 32629.

It is an arithmetic number, because the mean of its divisors is an integer number (2125530).

Almost surely, 2^21861007 is an apocalyptic number.

21861007 is a deficient number, since it is larger than the sum of its proper divisors (3645353).

21861007 is an equidigital number, since it uses as much as digits as its factorization.

21861007 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1350 (or 1343 counting only the distinct ones).

The product of its (nonzero) digits is 672, while the sum is 25.

The square root of 21861007 is about 4675.5755795410. The cubic root of 21861007 is about 279.6125892218.

Adding to 21861007 its reverse (70016812), we get a palindrome (91877819).

The spelling of 21861007 in words is "twenty-one million, eight hundred sixty-one thousand, seven".