21513043 has 4 divisors (see below), whose sum is σ = 21785440. Its totient is φ = 21240648.

The previous prime is 21513031. The next prime is 21513049. The reversal of 21513043 is 34031512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21513043 is a prime.

It is a super-2 number, since 2×21513043² = 925622038239698, 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 21513043.

It is not an unprimeable number, because it can be changed into a prime (21513049) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 136080 + ... + 136237.

It is an arithmetic number, because the mean of its divisors is an integer number (5446360).

Almost surely, 2^21513043 is an apocalyptic number.

21513043 is a deficient number, since it is larger than the sum of its proper divisors (272397).

21513043 is an equidigital number, since it uses as much as digits as its factorization.

21513043 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 272396.

The product of its (nonzero) digits is 360, while the sum is 19.

The square root of 21513043 is about 4638.2154973653. The cubic root of 21513043 is about 278.1211064219.

Adding to 21513043 its reverse (34031512), we get a palindrome (55544555).

The spelling of 21513043 in words is "twenty-one million, five hundred thirteen thousand, forty-three".