1521561020 has 96 divisors (see below), whose sum is σ = 3758565888. Its totient is φ = 506564352.

The previous prime is 1521561017. The next prime is 1521561023. The reversal of 1521561020 is 201651251.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (1521561017) and next prime (1521561023).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1521561023) by changing a digit.

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 31 ways as a sum of consecutive naturals, for example, 1185299 + ... + 1186581.

It is an arithmetic number, because the mean of its divisors is an integer number (39151728).

Almost surely, 2^1521561020 is an apocalyptic number.

1521561020 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 1521561020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1879282944).

1521561020 is an abundant number, since it is smaller than the sum of its proper divisors (2237004868).

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

1521561020 is a wasteful number, since it uses less digits than its factorization.

1521561020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1539 (or 1537 counting only the distinct ones).

The product of its (nonzero) digits is 600, while the sum is 23.

The square root of 1521561020 is about 39007.1919009815. The cubic root of 1521561020 is about 1150.1728839013.

The spelling of 1521561020 in words is "one billion, five hundred twenty-one million, five hundred sixty-one thousand, twenty".