19902109 has 2 divisors, whose sum is σ = 19902110. Its totient is φ = 19902108.

The previous prime is 19902073. The next prime is 19902119. The reversal of 19902109 is 90120991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19829209 + 72900 = 4453^2 + 270^2 .

It is a cyclic number.

It is not a de Polignac number, because 19902109 - 2¹⁵ = 19869341 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19902119) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9951054 + 9951055.

It is an arithmetic number, because the mean of its divisors is an integer number (9951055).

Almost surely, 2^19902109 is an apocalyptic number.

It is an amenable number.

19902109 is a deficient number, since it is larger than the sum of its proper divisors (1).

19902109 is an equidigital number, since it uses as much as digits as its factorization.

19902109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1458, while the sum is 31.

The square root of 19902109 is about 4461.1779834479. The cubic root of 19902109 is about 270.9981753938.

The spelling of 19902109 in words is "nineteen million, nine hundred two thousand, one hundred nine".