1021540 has 24 divisors (see below), whose sum is σ = 2310840. Its totient is φ = 377088.

The previous prime is 1021487. The next prime is 1021541. The reversal of 1021540 is 451201.

It can be written as a sum of positive squares in 4 ways, for example, as 5476 + 1016064 = 74^2 + 1008^2 .

It is a Harshad number since it is a multiple of its sum of digits (13).

It is a nialpdrome in base 16.

It is a self number, because there is not a number n which added to its sum of digits gives 1021540.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1021541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1705 + ... + 2224.

It is an arithmetic number, because the mean of its divisors is an integer number (96285).

2^1021540 is an apocalyptic number.

1021540 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1021540 is an abundant number, since it is smaller than the sum of its proper divisors (1289300).

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

1021540 is a wasteful number, since it uses less digits than its factorization.

1021540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3951 (or 3949 counting only the distinct ones).

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

The square root of 1021540 is about 1010.7126198876. The cubic root of 1021540 is about 100.7129055789.

Adding to 1021540 its reverse (451201), we get a palindrome (1472741).

It can be divided in two parts, 102 and 1540, that multiplied together give a triangular number (157080 = T₅₆₀).

The spelling of 1021540 in words is "one million, twenty-one thousand, five hundred forty".