1561941504 has 240 divisors, whose sum is σ = 4841261568. Its totient is φ = 483065856.

The previous prime is 1561941461. The next prime is 1561941509. The reversal of 1561941504 is 4051491651.

1561941504 is a `hidden beast` number, since 1 + 5 + 61 + 94 + 1 + 504 = 666.

It is a super-2 number, since 2×1561941504² = 4879322523835564032, which contains 22 as substring.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1561941509) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 9948594 + ... + 9948750.

Almost surely, 2^1561941504 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1561941504, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2420630784).

1561941504 is an abundant number, since it is smaller than the sum of its proper divisors (3279320064).

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

1561941504 is a wasteful number, since it uses less digits than its factorization.

1561941504 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 325 (or 306 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 36.

The square root of 1561941504 is about 39521.4056430183. The cubic root of 1561941504 is about 1160.2589354581.

The spelling of 1561941504 in words is "one billion, five hundred sixty-one million, nine hundred forty-one thousand, five hundred four".