1561209600 has 432 divisors, whose sum is σ = 5531423744. Its totient is φ = 387072000.

The previous prime is 1561209593. The next prime is 1561209647. The reversal of 1561209600 is 69021651.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 25593570 + ... + 25593630.

Almost surely, 2^1561209600 is an apocalyptic number.

1561209600 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 1561209600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2765711872).

1561209600 is an abundant number, since it is smaller than the sum of its proper divisors (3970214144).

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

1561209600 is a wasteful number, since it uses less digits than its factorization.

1561209600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 164 (or 145 counting only the distinct ones).

The product of its (nonzero) digits is 3240, while the sum is 30.

The square root of 1561209600 is about 39512.1449683512. The cubic root of 1561209600 is about 1160.0776800933.

The spelling of 1561209600 in words is "one billion, five hundred sixty-one million, two hundred nine thousand, six hundred".