1221520 has 20 divisors (see below), whose sum is σ = 2840220. Its totient is φ = 488576.

The previous prime is 1221503. The next prime is 1221523. The reversal of 1221520 is 251221.

It can be written as a sum of positive squares in 2 ways, for example, as 495616 + 725904 = 704^2 + 852^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a super-2 number, since 2×1221520² = 2984222220800, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1221520.

It is not an unprimeable number, because it can be changed into a prime (1221523) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7555 + ... + 7714.

It is an arithmetic number, because the mean of its divisors is an integer number (142011).

2^1221520 is an apocalyptic number.

1221520 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221520 is an abundant number, since it is smaller than the sum of its proper divisors (1618700).

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

1221520 is a wasteful number, since it uses less digits than its factorization.

1221520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15282 (or 15276 counting only the distinct ones).

The product of its (nonzero) digits is 40, while the sum is 13.

The square root of 1221520 is about 1105.2239592046. The cubic root of 1221520 is about 106.8973306963.

Adding to 1221520 its reverse (251221), we get a palindrome (1472741).

Subtracting from 1221520 its reverse (251221), we obtain a cube (970299 = 99³).

The spelling of 1221520 in words is "one million, two hundred twenty-one thousand, five hundred twenty".