66963821 has 4 divisors (see below), whose sum is σ = 68773692. Its totient is φ = 65153952.

The previous prime is 66963803. The next prime is 66963877. The reversal of 66963821 is 12836966.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 34633225 + 32330596 = 5885^2 + 5686^2 .

It is a cyclic number.

It is not a de Polignac number, because 66963821 - 2¹⁴ = 66947437 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66963121) 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, 904880 + ... + 904953.

It is an arithmetic number, because the mean of its divisors is an integer number (17193423).

Almost surely, 2^66963821 is an apocalyptic number.

It is an amenable number.

66963821 is a deficient number, since it is larger than the sum of its proper divisors (1809871).

66963821 is a wasteful number, since it uses less digits than its factorization.

66963821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1809870.

The product of its digits is 93312, while the sum is 41.

The square root of 66963821 is about 8183.1424892886. The cubic root of 66963821 is about 406.0816910368.

The spelling of 66963821 in words is "sixty-six million, nine hundred sixty-three thousand, eight hundred twenty-one".