1699900021 has 2 divisors, whose sum is σ = 1699900022. Its totient is φ = 1699900020.

The previous prime is 1699900003. The next prime is 1699900043. The reversal of 1699900021 is 1200099961.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1026497521 + 673402500 = 32039^2 + 25950^2 .

It is an emirp because it is prime and its reverse (1200099961) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1699900021 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1699900921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 849950010 + 849950011.

It is an arithmetic number, because the mean of its divisors is an integer number (849950011).

Almost surely, 2^1699900021 is an apocalyptic number.

It is an amenable number.

1699900021 is a deficient number, since it is larger than the sum of its proper divisors (1).

1699900021 is an equidigital number, since it uses as much as digits as its factorization.

1699900021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8748, while the sum is 37.

The square root of 1699900021 is about 41229.8438148873. The cubic root of 1699900021 is about 1193.4597947518.

Adding to 1699900021 its reverse (1200099961), we get a palindrome (2899999982).

The spelling of 1699900021 in words is "one billion, six hundred ninety-nine million, nine hundred thousand, twenty-one".