1020099721 has 15 divisors (see below), whose sum is σ = 1103530305. Its totient is φ = 942839280.

The previous prime is 1020099659. The next prime is 1020099727. The reversal of 1020099721 is 1279900201.

The square root of 1020099721 is 31939.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 2 ways, for example, as 832957321 + 187142400 = 28861^2 + 13680^2 .

It is not a de Polignac number, because 1020099721 - 2¹⁹ = 1019575433 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1020099727) by changing a digit.

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 14 ways as a sum of consecutive naturals, for example, 24880461 + ... + 24880501.

It is an arithmetic number, because the mean of its divisors is an integer number (73568687).

Almost surely, 2^1020099721 is an apocalyptic number.

1020099721 is the 31939-th square number.

1020099721 is the 15970-th centered octagonal number.

It is an amenable number.

1020099721 is a deficient number, since it is larger than the sum of its proper divisors (83430584).

1020099721 is an frugal number, since it uses more digits than its factorization.

1020099721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 202 (or 60 counting only the distinct ones).

The product of its (nonzero) digits is 2268, while the sum is 31.

The cubic root of 1020099721 is about 1006.6555128778.

Adding to 1020099721 its reverse (1279900201), we get a palindrome (2299999922).

The spelling of 1020099721 in words is "one billion, twenty million, ninety-nine thousand, seven hundred twenty-one".