61821869 has 4 divisors (see below), whose sum is σ = 61837596. Its totient is φ = 61806144.

The previous prime is 61821841. The next prime is 61821871. The reversal of 61821869 is 96812816.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 43072969 + 18748900 = 6563^2 + 4330^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-61821869 is a prime.

It is a super-3 number, since 3×61821869³ (a number of 24 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61821829) 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 3 ways as a sum of consecutive naturals, for example, 3827 + ... + 11759.

It is an arithmetic number, because the mean of its divisors is an integer number (15459399).

Almost surely, 2^61821869 is an apocalyptic number.

It is an amenable number.

61821869 is a deficient number, since it is larger than the sum of its proper divisors (15727).

61821869 is an equidigital number, since it uses as much as digits as its factorization.

61821869 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15726.

The product of its digits is 41472, while the sum is 41.

The square root of 61821869 is about 7862.6884079175. The cubic root of 61821869 is about 395.4097526528.

The spelling of 61821869 in words is "sixty-one million, eight hundred twenty-one thousand, eight hundred sixty-nine".