18771220 has 96 divisors (see below), whose sum is σ = 45948672. Its totient is φ = 6386688.

The previous prime is 18771209. The next prime is 18771223. The reversal of 18771220 is 2217781.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18771223) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 257104 + ... + 257176.

It is an arithmetic number, because the mean of its divisors is an integer number (478632).

Almost surely, 2^18771220 is an apocalyptic number.

18771220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18771220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22974336).

18771220 is an abundant number, since it is smaller than the sum of its proper divisors (27177452).

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

18771220 is a wasteful number, since it uses less digits than its factorization.

18771220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 161 (or 159 counting only the distinct ones).

The product of its (nonzero) digits is 1568, while the sum is 28.

The square root of 18771220 is about 4332.5766005923. The cubic root of 18771220 is about 265.7648250222.

The spelling of 18771220 in words is "eighteen million, seven hundred seventy-one thousand, two hundred twenty".