10721216021 has 6 divisors (see below), whose sum is σ = 11207623350. Its totient is φ = 10255075688.

The previous prime is 10721215969. The next prime is 10721216057. The reversal of 10721216021 is 12061212701.

It can be written as a sum of positive squares in only one way, i.e., 10325404996 + 395811025 = 101614^2 + 19895^2 .

It is not a de Polignac number, because 10721216021 - 2³⁰ = 9647474197 is a prime.

It is a super-2 number, since 2×10721216021² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (23).

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (10721216521) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 10132946 + ... + 10134003.

It is an arithmetic number, because the mean of its divisors is an integer number (1867937225).

Almost surely, 2^10721216021 is an apocalyptic number.

It is an amenable number.

10721216021 is a deficient number, since it is larger than the sum of its proper divisors (486407329).

10721216021 is an equidigital number, since it uses as much as digits as its factorization.

10721216021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20266995 (or 20266972 counting only the distinct ones).

The product of its (nonzero) digits is 336, while the sum is 23.

Adding to 10721216021 its reverse (12061212701), we get a palindrome (22782428722).

The spelling of 10721216021 in words is "ten billion, seven hundred twenty-one million, two hundred sixteen thousand, twenty-one".