66121531 has 12 divisors (see below), whose sum is σ = 77314800. Its totient is φ = 56382480.

The previous prime is 66121529. The next prime is 66121547. The reversal of 66121531 is 13512166.

It is not a de Polignac number, because 66121531 - 2¹ = 66121529 is a prime.

It is a super-2 number, since 2×66121531² = 8744113723567922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 66121496 and 66121505.

It is not an unprimeable number, because it can be changed into a prime (66121591) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6361 + ... + 13141.

It is an arithmetic number, because the mean of its divisors is an integer number (6442900).

Almost surely, 2^66121531 is an apocalyptic number.

66121531 is a deficient number, since it is larger than the sum of its proper divisors (11193269).

66121531 is a wasteful number, since it uses less digits than its factorization.

66121531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6994 (or 6987 counting only the distinct ones).

The product of its digits is 1080, while the sum is 25.

The square root of 66121531 is about 8131.5146805500. The cubic root of 66121531 is about 404.3718984224.

Adding to 66121531 its reverse (13512166), we get a palindrome (79633697).

The spelling of 66121531 in words is "sixty-six million, one hundred twenty-one thousand, five hundred thirty-one".