1021265520 has 160 divisors (see below), whose sum is σ = 3481277184. Its totient is φ = 245606400.

The previous prime is 1021265501. The next prime is 1021265543. The reversal of 1021265520 is 255621201.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is an unprimeable number.

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, 344364 + ... + 347316.

Almost surely, 2^1021265520 is an apocalyptic number.

1021265520 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 1021265520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1740638592).

1021265520 is an abundant number, since it is smaller than the sum of its proper divisors (2460011664).

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

1021265520 is a wasteful number, since it uses less digits than its factorization.

1021265520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3111 (or 3105 counting only the distinct ones).

The product of its (nonzero) digits is 1200, while the sum is 24.

The square root of 1021265520 is about 31957.2451879069. The cubic root of 1021265520 is about 1007.0388450793.

Adding to 1021265520 its reverse (255621201), we get a palindrome (1276886721).

The spelling of 1021265520 in words is "one billion, twenty-one million, two hundred sixty-five thousand, five hundred twenty".