18721740 has 24 divisors (see below), whose sum is σ = 52421040. Its totient is φ = 4992448.

The previous prime is 18721739. The next prime is 18721753. The reversal of 18721740 is 4712781.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 18721698 and 18721707.

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, 155955 + ... + 156074.

It is an arithmetic number, because the mean of its divisors is an integer number (2184210).

Almost surely, 2^18721740 is an apocalyptic number.

18721740 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18721740 is an abundant number, since it is smaller than the sum of its proper divisors (33699300).

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

18721740 is a wasteful number, since it uses less digits than its factorization.

18721740 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 312041 (or 312039 counting only the distinct ones).

The product of its (nonzero) digits is 3136, while the sum is 30.

The square root of 18721740 is about 4326.8626047056. The cubic root of 18721740 is about 265.5311052679.

The spelling of 18721740 in words is "eighteen million, seven hundred twenty-one thousand, seven hundred forty".