400018500 has 480 divisors, whose sum is σ = 1598268672. Its totient is φ = 85017600.

The previous prime is 400018471. The next prime is 400018501. The reversal of 400018500 is 5810004.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (400018501) by changing a digit.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 4819459 + ... + 4819541.

Almost surely, 2^400018500 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 400018500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (799134336).

400018500 is an abundant number, since it is smaller than the sum of its proper divisors (1198250172).

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

400018500 is a wasteful number, since it uses less digits than its factorization.

400018500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 138 (or 117 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 18.

The square root of 400018500 is about 20000.4624946525. The cubic root of 400018500 is about 736.8176586501.

Adding to 400018500 its reverse (5810004), we get a palindrome (405828504).

It can be divided in two parts, 4000 and 18500, that added together give a square (22500 = 150²).

The spelling of 400018500 in words is "four hundred million, eighteen thousand, five hundred".