21502543401461 has 2 divisors, whose sum is σ = 21502543401462. Its totient is φ = 21502543401460.

The previous prime is 21502543401359. The next prime is 21502543401463. The reversal of 21502543401461 is 16410434520512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15389811310225 + 6112732091236 = 3922985^2 + 2472394^2 .

It is a cyclic number.

It is not a de Polignac number, because 21502543401461 - 2¹⁸ = 21502543139317 is a prime.

Together with 21502543401463, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21502543401463) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10751271700730 + 10751271700731.

It is an arithmetic number, because the mean of its divisors is an integer number (10751271700731).

Almost surely, 2^{21502543401461} is an apocalyptic number.

It is an amenable number.

21502543401461 is a deficient number, since it is larger than the sum of its proper divisors (1).

21502543401461 is an equidigital number, since it uses as much as digits as its factorization.

21502543401461 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 115200, while the sum is 38.

Adding to 21502543401461 its reverse (16410434520512), we get a palindrome (37912977921973).

The spelling of 21502543401461 in words is "twenty-one trillion, five hundred two billion, five hundred forty-three million, four hundred one thousand, four hundred sixty-one".