1521816660 has 672 divisors, whose sum is σ = 6252029952. Its totient is φ = 302330880.

The previous prime is 1521816649. The next prime is 1521816661. The reversal of 1521816660 is 666181251.

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 (1521816661) by changing a digit.

It is a polite number, since it can be written in 223 ways as a sum of consecutive naturals, for example, 41130162 + ... + 41130198.

It is an arithmetic number, because the mean of its divisors is an integer number (9303616).

Almost surely, 2^1521816660 is an apocalyptic number.

1521816660 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 1521816660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3126014976).

1521816660 is an abundant number, since it is smaller than the sum of its proper divisors (4730213292).

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

1521816660 is a wasteful number, since it uses less digits than its factorization.

1521816660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 115 (or 98 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 36.

The square root of 1521816660 is about 39010.4685949810. The cubic root of 1521816660 is about 1150.2372944478.

It can be divided in two parts, 15218 and 16660, that added together give a triangular number (31878 = T₂₅₂).

The spelling of 1521816660 in words is "one billion, five hundred twenty-one million, eight hundred sixteen thousand, six hundred sixty".