21745336369 has 9 divisors (see below), whose sum is σ = 21872150827. Its totient is φ = 21619255504.

The previous prime is 21745336321. The next prime is 21745336373. The reversal of 21745336369 is 96363354712.

The square root of 21745336369 is 147463.

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., 629759025 + 21115577344 = 25095^2 + 145312^2 .

It is not a de Polignac number, because 21745336369 - 2²³ = 21736947761 is a prime.

It is a super-2 number, since 2×21745336369² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21745336309) 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, 35243349 + ... + 35243965.

Almost surely, 2^21745336369 is an apocalyptic number.

21745336369 is the 147463-rd square number.

21745336369 is the 73732-nd centered octagonal number.

It is an amenable number.

21745336369 is a deficient number, since it is larger than the sum of its proper divisors (126814458).

21745336369 is an frugal number, since it uses more digits than its factorization.

21745336369 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1712 (or 856 counting only the distinct ones).

The product of its digits is 2449440, while the sum is 49.

Multiplying 21745336369 by its sum of digits (49), we get a square (1065521482081 = 1032241²).

The spelling of 21745336369 in words is "twenty-one billion, seven hundred forty-five million, three hundred thirty-six thousand, three hundred sixty-nine".