161398440 has 256 divisors, whose sum is σ = 632563200. Its totient is φ = 35831808.

The previous prime is 161398421. The next prime is 161398463. The reversal of 161398440 is 44893161.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 161398395 and 161398404.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 279432 + ... + 280008.

It is an arithmetic number, because the mean of its divisors is an integer number (2470950).

Almost surely, 2^161398440 is an apocalyptic number.

161398440 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 161398440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (316281600).

161398440 is an abundant number, since it is smaller than the sum of its proper divisors (471164760).

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

161398440 is a wasteful number, since it uses less digits than its factorization.

161398440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 641 (or 631 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 36.

The square root of 161398440 is about 12704.2685739872. The cubic root of 161398440 is about 544.4605834758.

The spelling of 161398440 in words is "one hundred sixty-one million, three hundred ninety-eight thousand, four hundred forty".