1521660 has 48 divisors (see below), whose sum is σ = 4870656. Its totient is φ = 347712.

The previous prime is 1521649. The next prime is 1521671. The reversal of 1521660 is 661251.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (1521649) and next prime (1521671).

It is a Harshad number since it is a multiple of its sum of digits (21).

It is an Ulam number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1392 + ... + 2231.

It is an arithmetic number, because the mean of its divisors is an integer number (101472).

2^1521660 is an apocalyptic number.

1521660 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1521660 is an abundant number, since it is smaller than the sum of its proper divisors (3348996).

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

1521660 is a wasteful number, since it uses less digits than its factorization.

1521660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3642 (or 3640 counting only the distinct ones).

The product of its (nonzero) digits is 360, while the sum is 21.

The square root of 1521660 is about 1233.5558357853. Note that the first 3 decimals coincide. The cubic root of 1521660 is about 115.0197823561.

It can be divided in two parts, 15 and 21660, that multiplied together give a square (324900 = 570²).

The spelling of 1521660 in words is "one million, five hundred twenty-one thousand, six hundred sixty".