13781421 has 10 divisors (see below), whose sum is σ = 20587182. Its totient is φ = 9187560.

The previous prime is 13781413. The next prime is 13781423. The reversal of 13781421 is 12418731.

13781421 is digitally balanced in base 2 and base 3, because in such bases it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 8555625 + 5225796 = 2925^2 + 2286^2 .

It is not a de Polignac number, because 13781421 - 2³ = 13781413 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13781423) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 84990 + ... + 85151.

Almost surely, 2^13781421 is an apocalyptic number.

It is an amenable number.

13781421 is a deficient number, since it is larger than the sum of its proper divisors (6805761).

13781421 is an equidigital number, since it uses as much as digits as its factorization.

13781421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 170153 (or 170144 counting only the distinct ones).

The product of its digits is 1344, while the sum is 27.

The square root of 13781421 is about 3712.3336326359. Note that the first 3 decimals coincide. The cubic root of 13781421 is about 239.7533403327.

The spelling of 13781421 in words is "thirteen million, seven hundred eighty-one thousand, four hundred twenty-one".