21661262141 has 2 divisors, whose sum is σ = 21661262142. Its totient is φ = 21661262140.

The previous prime is 21661262107. The next prime is 21661262143. The reversal of 21661262141 is 14126216612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21058363225 + 602898916 = 145115^2 + 24554^2 .

It is a cyclic number.

It is not a de Polignac number, because 21661262141 - 2¹⁴ = 21661245757 is a prime.

It is a super-2 number, since 2×21661262141² (a number of 21 digits) contains 22 as substring.

Together with 21661262143, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21661262098 and 21661262107.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21661262143) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10830631070 + 10830631071.

It is an arithmetic number, because the mean of its divisors is an integer number (10830631071).

Almost surely, 2^21661262141 is an apocalyptic number.

It is an amenable number.

21661262141 is a deficient number, since it is larger than the sum of its proper divisors (1).

21661262141 is an equidigital number, since it uses as much as digits as its factorization.

21661262141 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6912, while the sum is 32.

Adding to 21661262141 its reverse (14126216612), we get a palindrome (35787478753).

The spelling of 21661262141 in words is "twenty-one billion, six hundred sixty-one million, two hundred sixty-two thousand, one hundred forty-one".