21520007644206 has 32 divisors (see below), whose sum is σ = 45323794460160. Its totient is φ = 6793014606336.

The previous prime is 21520007644127. The next prime is 21520007644207. The reversal of 21520007644206 is 60244670002512.

It is a super-2 number, since 2×21520007644206² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21520007644207) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 38293171 + ... + 38851086.

It is an arithmetic number, because the mean of its divisors is an integer number (1416368576880).

Almost surely, 2^{21520007644206} is an apocalyptic number.

21520007644206 is an abundant number, since it is smaller than the sum of its proper divisors (23803786815954).

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

21520007644206 is a wasteful number, since it uses less digits than its factorization.

21520007644206 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77146728.

The product of its (nonzero) digits is 161280, while the sum is 39.

Adding to 21520007644206 its reverse (60244670002512), we get a palindrome (81764677646718).

The spelling of 21520007644206 in words is "twenty-one trillion, five hundred twenty billion, seven million, six hundred forty-four thousand, two hundred six".