190018399921 has 9 divisors (see below), whose sum is σ = 221045361771. Its totient is φ = 162870298752.

The previous prime is 190018399859. The next prime is 190018399943. The reversal of 190018399921 is 129993810091.

It is a happy number.

The square root of 190018399921 is 435911.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 67753487025 + 122264912896 = 260295^2 + 349664^2 .

It is not a de Polignac number, because 190018399921 - 2¹³ = 190018391729 is a prime.

It is a super-2 number, since 2×190018399921² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (190018399981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 3020241 + ... + 3082513.

Almost surely, 2^190018399921 is an apocalyptic number.

190018399921 is the 435911-st square number.

190018399921 is the 217956-th centered octagonal number.

It is an amenable number.

190018399921 is a deficient number, since it is larger than the sum of its proper divisors (31026961850).

190018399921 is an frugal number, since it uses more digits than its factorization.

190018399921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 124560 (or 62280 counting only the distinct ones).

The product of its (nonzero) digits is 314928, while the sum is 52.

The spelling of 190018399921 in words is "one hundred ninety billion, eighteen million, three hundred ninety-nine thousand, nine hundred twenty-one".