1561940 has 24 divisors (see below), whose sum is σ = 3394440. Its totient is φ = 603008.

The previous prime is 1561919. The next prime is 1562051. The reversal of 1561940 is 491651.

It can be written as a sum of positive squares in 4 ways, for example, as 126736 + 1435204 = 356^2 + 1198^2 .

It is an Ulam number.

It is a congruent number.

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, 767 + ... + 1926.

It is an arithmetic number, because the mean of its divisors is an integer number (141435).

2^1561940 is an apocalyptic number.

1561940 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1561940 is an abundant number, since it is smaller than the sum of its proper divisors (1832500).

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

1561940 is a wasteful number, since it uses less digits than its factorization.

1561940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2731 (or 2729 counting only the distinct ones).

The product of its (nonzero) digits is 1080, while the sum is 26.

The square root of 1561940 is about 1249.7759799260. The cubic root of 1561940 is about 116.0258563052.

The spelling of 1561940 in words is "one million, five hundred sixty-one thousand, nine hundred forty".