21145861962369 has 45 divisors (see below), whose sum is σ = 31309028429523. Its totient is φ = 13752788838768.

The previous prime is 21145861962341. The next prime is 21145861962457. The reversal of 21145861962369 is 96326916854112.

The square root of 21145861962369 is 4598463.

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

21145861962369 is a `hidden beast` number, since 2 + 1 + 1 + 4 + 5 + 8 + 619 + 6 + 2 + 3 + 6 + 9 = 666.

It can be written as a sum of positive squares in only one way, i.e., 12173560617969 + 8972301344400 = 3489063^2 + 2995380^2 .

It is not a de Polignac number, because 21145861962369 - 2²¹ = 21145859865217 is a prime.

It is a super-2 number, since 2×21145861962369² (a number of 27 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21145861967369) by changing a digit.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 25507673847 + ... + 25507674675.

Almost surely, 2^{21145861962369} is an apocalyptic number.

21145861962369 is the 4598463-rd square number.

21145861962369 is the 2299232-nd centered octagonal number.

It is an amenable number.

21145861962369 is a deficient number, since it is larger than the sum of its proper divisors (10163166467154).

21145861962369 is an frugal number, since it uses more digits than its factorization.

21145861962369 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1836 (or 875 counting only the distinct ones).

The product of its digits is 33592320, while the sum is 63.

The spelling of 21145861962369 in words is "twenty-one trillion, one hundred forty-five billion, eight hundred sixty-one million, nine hundred sixty-two thousand, three hundred sixty-nine".