13721566 has 4 divisors (see below), whose sum is σ = 20582352. Its totient is φ = 6860782.

The previous prime is 13721563. The next prime is 13721569. The reversal of 13721566 is 66512731.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 66512731 = 1801 ⋅36931.

It is an interprime number because it is at equal distance from previous prime (13721563) and next prime (13721569).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13721563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3430390 + ... + 3430393.

It is an arithmetic number, because the mean of its divisors is an integer number (5145588).

Almost surely, 2^13721566 is an apocalyptic number.

13721566 is a deficient number, since it is larger than the sum of its proper divisors (6860786).

13721566 is an equidigital number, since it uses as much as digits as its factorization.

13721566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6860785.

The product of its digits is 7560, while the sum is 31.

The square root of 13721566 is about 3704.2632195890. The cubic root of 13721566 is about 239.4057404274.

The spelling of 13721566 in words is "thirteen million, seven hundred twenty-one thousand, five hundred sixty-six".