1669921021 has 8 divisors (see below), whose sum is σ = 1713346488. Its totient is φ = 1626624000.

The previous prime is 1669921013. The next prime is 1669921027. The reversal of 1669921021 is 1201299661.

It can be written as a sum of positive squares in 4 ways, for example, as 408605796 + 1261315225 = 20214^2 + 35515^2 .

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 1669921021 - 2³ = 1669921013 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 (1669921027) 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, 5490 + ... + 58051.

It is an arithmetic number, because the mean of its divisors is an integer number (214168311).

Almost surely, 2^1669921021 is an apocalyptic number.

It is an amenable number.

1669921021 is a deficient number, since it is larger than the sum of its proper divisors (43425467).

1669921021 is an equidigital number, since it uses as much as digits as its factorization.

1669921021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 64223.

The product of its (nonzero) digits is 11664, while the sum is 37.

The square root of 1669921021 is about 40864.6671465705. The cubic root of 1669921021 is about 1186.4022925111.

The spelling of 1669921021 in words is "one billion, six hundred sixty-nine million, nine hundred twenty-one thousand, twenty-one".