400890 has 64 divisors (see below), whose sum is σ = 1161216. Its totient is φ = 86592.

The previous prime is 400871. The next prime is 400903. The reversal of 400890 is 98004.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is an unprimeable number.

400890 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4789 + ... + 4871.

It is an arithmetic number, because the mean of its divisors is an integer number (18144).

2⁴⁰⁰⁸⁹⁰ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 400890, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (580608).

400890 is an abundant number, since it is smaller than the sum of its proper divisors (760326).

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

400890 is a wasteful number, since it uses less digits than its factorization.

400890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 123.

The product of its (nonzero) digits is 288, while the sum is 21.

The square root of 400890 is about 633.1587478666. The cubic root of 400890 is about 73.7352359606.

Adding to 400890 its reverse (98004), we get a palindrome (498894).

The spelling of 400890 in words is "four hundred thousand, eight hundred ninety".