21513519 has 20 divisors (see below), whose sum is σ = 32299256. Its totient is φ = 14329224.

The previous prime is 21513511. The next prime is 21513523. The reversal of 21513519 is 91531512.

It is not a de Polignac number, because 21513519 - 2³ = 21513511 is a prime.

It is a super-2 number, since 2×21513519² = 925662999526722, which contains 22 as substring.

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

It is a Duffinian number.

It is a nialpdrome in base 3 and base 9.

It is a zygodrome in base 3.

It is a junction number, because it is equal to n+sod(n) for n = 21513492 and 21513501.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21513511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 19137 + ... + 20229.

Almost surely, 2^21513519 is an apocalyptic number.

21513519 is a deficient number, since it is larger than the sum of its proper divisors (10785737).

21513519 is an frugal number, since it uses more digits than its factorization.

21513519 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1120 (or 1096 counting only the distinct ones).

The product of its digits is 1350, while the sum is 27.

The square root of 21513519 is about 4638.2668099194. The cubic root of 21513519 is about 278.1231576531.

The spelling of 21513519 in words is "twenty-one million, five hundred thirteen thousand, five hundred nineteen".