63686821 has 4 divisors (see below), whose sum is σ = 69476544. Its totient is φ = 57897100.

The previous prime is 63686807. The next prime is 63686851. The reversal of 63686821 is 12868636.

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 a cyclic number.

It is not a de Polignac number, because 63686821 - 2⁵ = 63686789 is a prime.

It is a super-2 number, since 2×63686821² = 8112022338172082, which contains 22 as substring.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (63686851) 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, 2894845 + ... + 2894866.

It is an arithmetic number, because the mean of its divisors is an integer number (17369136).

Almost surely, 2^63686821 is an apocalyptic number.

It is an amenable number.

63686821 is a deficient number, since it is larger than the sum of its proper divisors (5789723).

63686821 is a wasteful number, since it uses less digits than its factorization.

63686821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5789722.

The product of its digits is 82944, while the sum is 40.

The square root of 63686821 is about 7980.4023081546. The cubic root of 63686821 is about 399.3464765994.

The spelling of 63686821 in words is "sixty-three million, six hundred eighty-six thousand, eight hundred twenty-one".