21984742541 has 2 divisors, whose sum is σ = 21984742542. Its totient is φ = 21984742540.

The previous prime is 21984742517. The next prime is 21984742583. The reversal of 21984742541 is 14524748912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20633886025 + 1350856516 = 143645^2 + 36754^2 .

It is a cyclic number.

It is not a de Polignac number, because 21984742541 - 2⁶ = 21984742477 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21984732541) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10992371270 + 10992371271.

It is an arithmetic number, because the mean of its divisors is an integer number (10992371271).

Almost surely, 2^21984742541 is an apocalyptic number.

It is an amenable number.

21984742541 is a deficient number, since it is larger than the sum of its proper divisors (1).

21984742541 is an equidigital number, since it uses as much as digits as its factorization.

21984742541 is an evil number, because the sum of its binary digits is even.

The product of its digits is 645120, while the sum is 47.

The spelling of 21984742541 in words is "twenty-one billion, nine hundred eighty-four million, seven hundred forty-two thousand, five hundred forty-one".