1561421040 has 160 divisors (see below), whose sum is σ = 5008179456. Its totient is φ = 402155520.

The previous prime is 1561421039. The next prime is 1561421047. The reversal of 1561421040 is 401241651.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 1561421040.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1561421047) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1052139 + ... + 1053621.

Almost surely, 2^1561421040 is an apocalyptic number.

1561421040 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 1561421040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2504089728).

1561421040 is an abundant number, since it is smaller than the sum of its proper divisors (3446758416).

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

1561421040 is a wasteful number, since it uses less digits than its factorization.

1561421040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1647 (or 1641 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 24.

The square root of 1561421040 is about 39514.8205107906. The cubic root of 1561421040 is about 1160.1300488361.

Adding to 1561421040 its reverse (401241651), we get a palindrome (1962662691).

The spelling of 1561421040 in words is "one billion, five hundred sixty-one million, four hundred twenty-one thousand, forty".