172218401861 has 8 divisors (see below), whose sum is σ = 187911964800. Its totient is φ = 156531063040.

The previous prime is 172218401843. The next prime is 172218401863. The reversal of 172218401861 is 168104812271.

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

It is a de Polignac number, because none of the positive numbers 2^k-172218401861 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 (172218401863) 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, 1498076 + ... + 1608933.

It is an arithmetic number, because the mean of its divisors is an integer number (23488995600).

Almost surely, 2^172218401861 is an apocalyptic number.

172218401861 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

172218401861 is a deficient number, since it is larger than the sum of its proper divisors (15693562939).

172218401861 is a wasteful number, since it uses less digits than its factorization.

172218401861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3112059.

The product of its (nonzero) digits is 43008, while the sum is 41.

The spelling of 172218401861 in words is "one hundred seventy-two billion, two hundred eighteen million, four hundred one thousand, eight hundred sixty-one".