21374641806 has 32 divisors (see below), whose sum is σ = 50541027840. Its totient is φ = 5896452576.

The previous prime is 21374641787. The next prime is 21374641843. The reversal of 21374641806 is 60814647312.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8773266 + ... + 8775701.

It is an arithmetic number, because the mean of its divisors is an integer number (1579407120).

Almost surely, 2^21374641806 is an apocalyptic number.

21374641806 is an abundant number, since it is smaller than the sum of its proper divisors (29166386034).

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

21374641806 is a wasteful number, since it uses less digits than its factorization.

21374641806 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17549008.

The product of its (nonzero) digits is 193536, while the sum is 42.

It can be divided in two parts, 213746 and 41806, that added together give a palindrome (255552).

The spelling of 21374641806 in words is "twenty-one billion, three hundred seventy-four million, six hundred forty-one thousand, eight hundred six".