61786821 has 4 divisors (see below), whose sum is σ = 82382432. Its totient is φ = 41191212.

The previous prime is 61786819. The next prime is 61786847. The reversal of 61786821 is 12868716.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 61786821 - 2¹ = 61786819 is a prime.

It is a super-2 number, since 2×61786821² = 7635222498572082, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 61786821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61786871) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10297801 + ... + 10297806.

It is an arithmetic number, because the mean of its divisors is an integer number (20595608).

Almost surely, 2^61786821 is an apocalyptic number.

It is an amenable number.

61786821 is a deficient number, since it is larger than the sum of its proper divisors (20595611).

61786821 is a wasteful number, since it uses less digits than its factorization.

61786821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20595610.

The product of its digits is 32256, while the sum is 39.

The square root of 61786821 is about 7860.4593377232. The cubic root of 61786821 is about 395.3350167441.

The spelling of 61786821 in words is "sixty-one million, seven hundred eighty-six thousand, eight hundred twenty-one".