42135820246521 has 9 divisors (see below), whose sum is σ = 60862879595791. Its totient is φ = 28090533848592.

The previous prime is 42135820246493. The next prime is 42135820246591. The reversal of 42135820246521 is 12564202853124.

The square root of 42135820246521 is 6491211.

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

42135820246521 is a `hidden beast` number, since 4 + 2 + 1 + 3 + 5 + 82 + 0 + 2 + 46 + 521 = 666.

It can be written as a sum of positive squares in only one way, i.e., 41687102468025 + 448717778496 = 6456555^2 + 669864^2 .

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 42135820246521 - 2⁵ = 42135820246489 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (42135820246591) 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, 18391765 + ... + 20555501.

Almost surely, 2^{42135820246521} is an apocalyptic number.

42135820246521 is the 6491211-st square number.

42135820246521 is the 3245606-th centered octagonal number.

It is an amenable number.

42135820246521 is a deficient number, since it is larger than the sum of its proper divisors (18727059349270).

42135820246521 is an frugal number, since it uses more digits than its factorization.

42135820246521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4327480 (or 2163740 counting only the distinct ones).

The product of its (nonzero) digits is 921600, while the sum is 45.

The spelling of 42135820246521 in words is "forty-two trillion, one hundred thirty-five billion, eight hundred twenty million, two hundred forty-six thousand, five hundred twenty-one".