16513981 has 8 divisors (see below), whose sum is σ = 18311328. Its totient is φ = 14766000.

The previous prime is 16513949. The next prime is 16513997. The reversal of 16513981 is 18931561.

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 16513981 - 2⁵ = 16513949 is a prime.

It is a super-2 number, since 2×16513981² = 545423136936722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16513781) 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, 11635 + ... + 12976.

It is an arithmetic number, because the mean of its divisors is an integer number (2288916).

Almost surely, 2^16513981 is an apocalyptic number.

16513981 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

16513981 is a deficient number, since it is larger than the sum of its proper divisors (1797347).

16513981 is a wasteful number, since it uses less digits than its factorization.

16513981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24683.

The product of its digits is 6480, while the sum is 34.

The square root of 16513981 is about 4063.7397800548. The cubic root of 16513981 is about 254.6540535024.

The spelling of 16513981 in words is "sixteen million, five hundred thirteen thousand, nine hundred eighty-one".