21365961241 has 9 divisors (see below), whose sum is σ = 21480437631. Its totient is φ = 21252094032.

The previous prime is 21365961229. The next prime is 21365961269. The reversal of 21365961241 is 14216956312.

The square root of 21365961241 is 146171.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 136305625 + 21229655616 = 11675^2 + 145704^2 .

It is not a de Polignac number, because 21365961241 - 2⁵ = 21365961209 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21365961194 and 21365961203.

It is not an unprimeable number, because it can be changed into a prime (21365961341) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 45751290 + ... + 45751756.

Almost surely, 2^21365961241 is an apocalyptic number.

21365961241 is the 146171-st square number.

21365961241 is the 73086-th centered octagonal number.

It is an amenable number.

21365961241 is a deficient number, since it is larger than the sum of its proper divisors (114476390).

21365961241 is an frugal number, since it uses more digits than its factorization.

21365961241 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1560 (or 780 counting only the distinct ones).

The product of its digits is 77760, while the sum is 40.

The spelling of 21365961241 in words is "twenty-one billion, three hundred sixty-five million, nine hundred sixty-one thousand, two hundred forty-one".