1561977564 has 192 divisors, whose sum is σ = 4505518080. Its totient is φ = 411586560.

The previous prime is 1561977551. The next prime is 1561977577. The reversal of 1561977564 is 4657791651.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (1561977551) and next prime (1561977577).

Its product of digits (1587600) is a multiple of the sum of its prime factors (360).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 8093052 + ... + 8093244.

It is an arithmetic number, because the mean of its divisors is an integer number (23466240).

Almost surely, 2^1561977564 is an apocalyptic number.

1561977564 is a gapful number since it is divisible by the number (14) 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 1561977564, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2252759040).

1561977564 is an abundant number, since it is smaller than the sum of its proper divisors (2943540516).

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

1561977564 is a wasteful number, since it uses less digits than its factorization.

1561977564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 360 (or 358 counting only the distinct ones).

The product of its digits is 1587600, while the sum is 51.

The square root of 1561977564 is about 39521.8618488552. The cubic root of 1561977564 is about 1160.2678642208.

The spelling of 1561977564 in words is "one billion, five hundred sixty-one million, nine hundred seventy-seven thousand, five hundred sixty-four".