19907945 has 4 divisors (see below), whose sum is σ = 23889540. Its totient is φ = 15926352.

The previous prime is 19907929. The next prime is 19907959. The reversal of 19907945 is 54970991.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 54970991 = 233 ⋅235927.

It can be written as a sum of positive squares in 2 ways, for example, as 4376464 + 15531481 = 2092^2 + 3941^2 .

It is a cyclic number.

It is not a de Polignac number, because 19907945 - 2⁴ = 19907929 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 19907896 and 19907905.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1990790 + ... + 1990799.

It is an arithmetic number, because the mean of its divisors is an integer number (5972385).

Almost surely, 2^19907945 is an apocalyptic number.

It is an amenable number.

19907945 is a deficient number, since it is larger than the sum of its proper divisors (3981595).

19907945 is an equidigital number, since it uses as much as digits as its factorization.

19907945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3981594.

The product of its (nonzero) digits is 102060, while the sum is 44.

The square root of 19907945 is about 4461.8320228355. The cubic root of 19907945 is about 271.0246615448.

The spelling of 19907945 in words is "nineteen million, nine hundred seven thousand, nine hundred forty-five".