18261620 has 24 divisors (see below), whose sum is σ = 41299944. Its totient is φ = 6742656.

The previous prime is 18261611. The next prime is 18261623. The reversal of 18261620 is 2616281.

It can be written as a sum of positive squares in 4 ways, for example, as 2085136 + 16176484 = 1444^2 + 4022^2 .

It is a Harshad number since it is a multiple of its sum of digits (26).

It is a self number, because there is not a number n which added to its sum of digits gives 18261620.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18261623) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 34859 + ... + 35378.

It is an arithmetic number, because the mean of its divisors is an integer number (1720831).

Almost surely, 2^18261620 is an apocalyptic number.

18261620 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18261620 is an abundant number, since it is smaller than the sum of its proper divisors (23038324).

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

18261620 is a wasteful number, since it uses less digits than its factorization.

18261620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70259 (or 70257 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 26.

The square root of 18261620 is about 4273.3616743730. The cubic root of 18261620 is about 263.3377378245.

It can be divided in two parts, 18261 and 620, that added together give a palindrome (18881).

The spelling of 18261620 in words is "eighteen million, two hundred sixty-one thousand, six hundred twenty".