21861006 has 16 divisors (see below), whose sum is σ = 44904144. Its totient is φ = 7089984.

The previous prime is 21860977. The next prime is 21861013. The reversal of 21861006 is 60016812.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 49015 + ... + 49458.

It is an arithmetic number, because the mean of its divisors is an integer number (2806509).

Almost surely, 2^21861006 is an apocalyptic number.

21861006 is an abundant number, since it is smaller than the sum of its proper divisors (23043138).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21861006 is a wasteful number, since it uses less digits than its factorization.

21861006 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 98515.

The product of its (nonzero) digits is 576, while the sum is 24.

The square root of 21861006 is about 4675.5754726023. The cubic root of 21861006 is about 279.6125849583.

Adding to 21861006 its reverse (60016812), we get a palindrome (81877818).

The spelling of 21861006 in words is "twenty-one million, eight hundred sixty-one thousand, six".