82161621 has 10 divisors (see below), whose sum is σ = 122735382. Its totient is φ = 54774360.

The previous prime is 82161613. The next prime is 82161641. The reversal of 82161621 is 12616128.

82161621 is a `hidden beast` number, since 8 + 21 + 616 + 21 = 666.

It can be written as a sum of positive squares in only one way, i.e., 76212900 + 5948721 = 8730^2 + 2439^2 .

It is not a de Polignac number, because 82161621 - 2³ = 82161613 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (82161601) 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 9 ways as a sum of consecutive naturals, for example, 507090 + ... + 507251.

Almost surely, 2^82161621 is an apocalyptic number.

82161621 is a gapful number since it is divisible by the number (81) formed by its first and last digit.

It is an amenable number.

82161621 is a deficient number, since it is larger than the sum of its proper divisors (40573761).

82161621 is a wasteful number, since it uses less digits than its factorization.

82161621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1014353 (or 1014344 counting only the distinct ones).

The product of its digits is 1152, while the sum is 27.

The square root of 82161621 is about 9064.3047720164. The cubic root of 82161621 is about 434.7333919227.

Adding to 82161621 its reverse (12616128), we get a palindrome (94777749).

The spelling of 82161621 in words is "eighty-two million, one hundred sixty-one thousand, six hundred twenty-one".