2621210121261 has 28 divisors (see below), whose sum is σ = 3931858741372. Its totient is φ = 1746654653376.

The previous prime is 2621210121251. The next prime is 2621210121301. The reversal of 2621210121261 is 1621210121262.

It is a happy number.

2621210121261 is a `hidden beast` number, since 2 + 621 + 2 + 1 + 0 + 12 + 1 + 26 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 1336784565636 + 1284425555625 = 1156194^2 + 1133325^2 .

It is not a de Polignac number, because 2621210121261 - 2⁶ = 2621210121197 is a prime.

It is a super-2 number, since 2×2621210121261² (a number of 26 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

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 (2621210121221) 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 27 ways as a sum of consecutive naturals, for example, 716595 + ... + 2399151.

Almost surely, 2^{2621210121261} is an apocalyptic number.

It is an amenable number.

2621210121261 is a deficient number, since it is larger than the sum of its proper divisors (1310648620111).

2621210121261 is an equidigital number, since it uses as much as digits as its factorization.

2621210121261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1684712 (or 1684697 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 27.

Subtracting from 2621210121261 its reverse (1621210121262), we obtain a palindrome (999999999999).

The spelling of 2621210121261 in words is "two trillion, six hundred twenty-one billion, two hundred ten million, one hundred twenty-one thousand, two hundred sixty-one".