20987567525961 has 27 divisors (see below), whose sum is σ = 30376742422221. Its totient is φ = 13963445562744.

The previous prime is 20987567525927. The next prime is 20987567525971. The reversal of 20987567525961 is 16952576578902.

The square root of 20987567525961 is 4581219.

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

20987567525961 is a `hidden beast` number, since 2 + 0 + 9 + 8 + 7 + 5 + 6 + 7 + 525 + 96 + 1 = 666.

It is not a de Polignac number, because 20987567525961 - 2⁷ = 20987567525833 is a prime.

It is a super-3 number, since 3×20987567525961³ (a number of 41 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 20987567525961.

It is not an unprimeable number, because it can be changed into a prime (20987567525971) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 8507322450 + ... + 8507324916.

Almost surely, 2^{20987567525961} is an apocalyptic number.

20987567525961 is the 4581219-th square number.

20987567525961 is the 2290610-th centered octagonal number.

It is an amenable number.

20987567525961 is a deficient number, since it is larger than the sum of its proper divisors (9389174896260).

20987567525961 is an frugal number, since it uses more digits than its factorization.

20987567525961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6178 (or 3089 counting only the distinct ones).

The product of its (nonzero) digits is 571536000, while the sum is 72.

The spelling of 20987567525961 in words is "twenty trillion, nine hundred eighty-seven billion, five hundred sixty-seven million, five hundred twenty-five thousand, nine hundred sixty-one".