6721221151620 has 36 divisors (see below), whose sum is σ = 20387704160460. Its totient is φ = 1792325640384.

The previous prime is 6721221151613. The next prime is 6721221151627. The reversal of 6721221151620 is 261511221276.

6721221151620 is a `hidden beast` number, since 6 + 7 + 2 + 1 + 2 + 21 + 1 + 5 + 1 + 620 = 666.

It is an interprime number because it is at equal distance from previous prime (6721221151613) and next prime (6721221151627).

It can be written as a sum of positive squares in 2 ways, for example, as 779025125376 + 5942196026244 = 882624^2 + 2437662^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (6721221151627) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 18670058575 + ... + 18670058934.

Almost surely, 2^{6721221151620} is an apocalyptic number.

6721221151620 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

6721221151620 is an abundant number, since it is smaller than the sum of its proper divisors (13666483008840).

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

6721221151620 is a wasteful number, since it uses less digits than its factorization.

6721221151620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37340117524 (or 37340117519 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 36.

Adding to 6721221151620 its reverse (261511221276), we get a palindrome (6982732372896).

The spelling of 6721221151620 in words is "six trillion, seven hundred twenty-one billion, two hundred twenty-one million, one hundred fifty-one thousand, six hundred twenty".