19915381 has 8 divisors (see below), whose sum is σ = 21601944. Its totient is φ = 18286080.

The previous prime is 19915369. The next prime is 19915387. The reversal of 19915381 is 18351991.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 255025 + 19660356 = 505^2 + 4434^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 19915381 - 2⁷ = 19915253 is a prime.

It is a super-2 number, since 2×19915381² = 793244800750322, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 19915381.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19915387) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13590 + ... + 14983.

It is an arithmetic number, because the mean of its divisors is an integer number (2700243).

Almost surely, 2^19915381 is an apocalyptic number.

It is an amenable number.

19915381 is a deficient number, since it is larger than the sum of its proper divisors (1686563).

19915381 is a wasteful number, since it uses less digits than its factorization.

19915381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28631.

The product of its digits is 9720, while the sum is 37.

The square root of 19915381 is about 4462.6652350361. The cubic root of 19915381 is about 271.0584016506.

The spelling of 19915381 in words is "nineteen million, nine hundred fifteen thousand, three hundred eighty-one".