1899401821 has 2 divisors, whose sum is σ = 1899401822. Its totient is φ = 1899401820.

The previous prime is 1899401813. The next prime is 1899401897. The reversal of 1899401821 is 1281049981.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1493822500 + 405579321 = 38650^2 + 20139^2 .

It is a cyclic number.

It is not a de Polignac number, because 1899401821 - 2³ = 1899401813 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1899401221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 949700910 + 949700911.

It is an arithmetic number, because the mean of its divisors is an integer number (949700911).

Almost surely, 2^1899401821 is an apocalyptic number.

It is an amenable number.

1899401821 is a deficient number, since it is larger than the sum of its proper divisors (1).

1899401821 is an equidigital number, since it uses as much as digits as its factorization.

1899401821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 41472, while the sum is 43.

The square root of 1899401821 is about 43582.1273115483. The cubic root of 1899401821 is about 1238.4323366933.

The spelling of 1899401821 in words is "one billion, eight hundred ninety-nine million, four hundred one thousand, eight hundred twenty-one".