25536531021 has 16 divisors (see below), whose sum is σ = 34561116288. Its totient is φ = 16768606400.

The previous prime is 25536531019. The next prime is 25536531023. The reversal of 25536531021 is 12013563552.

It is a happy number.

25536531021 is a nontrivial binomial coefficient, being equal to C(225994, 2).

It is an interprime number because it is at equal distance from previous prime (25536531019) and next prime (25536531023).

It is a 3-Lehmer number, since φ(25536531021) divides (25536531021-1)³.

It is a cyclic number.

It is a Carmichael number.

It is not a de Polignac number, because 25536531021 - 2¹ = 25536531019 is a prime.

It is a super-2 number, since 2×25536531021² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25536531023) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 169495 + ... + 282491.

It is an arithmetic number, because the mean of its divisors is an integer number (2160069768).

It is a Poulet number, since it divides 2^25536531020-1.

Almost surely, 2^25536531021 is an apocalyptic number.

25536531021 is the 225993-rd triangular number and also the 112997-th hexagonal number.

It is an amenable number.

25536531021 is a deficient number, since it is larger than the sum of its proper divisors (9024585267).

25536531021 is a wasteful number, since it uses less digits than its factorization.

25536531021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 114132.

The product of its (nonzero) digits is 27000, while the sum is 33.

The spelling of 25536531021 in words is "twenty-five billion, five hundred thirty-six million, five hundred thirty-one thousand, twenty-one".