1966491821 has 8 divisors (see below), whose sum is σ = 2261208384. Its totient is φ = 1675222560.

The previous prime is 1966491817. The next prime is 1966491883. The reversal of 1966491821 is 1281946691.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1966491821 - 2² = 1966491817 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 (1966491721) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 860600 + ... + 862881.

It is an arithmetic number, because the mean of its divisors is an integer number (282651048).

Almost surely, 2^1966491821 is an apocalyptic number.

It is an amenable number.

1966491821 is a deficient number, since it is larger than the sum of its proper divisors (294716563).

1966491821 is a wasteful number, since it uses less digits than its factorization.

1966491821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1723651.

The product of its digits is 186624, while the sum is 47.

The square root of 1966491821 is about 44345.1442775869. The cubic root of 1966491821 is about 1252.8451078559.

The spelling of 1966491821 in words is "one billion, nine hundred sixty-six million, four hundred ninety-one thousand, eight hundred twenty-one".