21513965 has 8 divisors (see below), whose sum is σ = 28163808. Its totient is φ = 15646480.

The previous prime is 21513949. The next prime is 21513967. The reversal of 21513965 is 56931512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21513965 - 2⁴ = 21513949 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21513967) 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, 195527 + ... + 195636.

It is an arithmetic number, because the mean of its divisors is an integer number (3520476).

Almost surely, 2^21513965 is an apocalyptic number.

It is an amenable number.

21513965 is a deficient number, since it is larger than the sum of its proper divisors (6649843).

21513965 is a wasteful number, since it uses less digits than its factorization.

21513965 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 391179.

The product of its digits is 8100, while the sum is 32.

The square root of 21513965 is about 4638.3148879739. The cubic root of 21513965 is about 278.1250795775.

It can be divided in two parts, 2151 and 3965, that added together give a palindrome (6116).

The spelling of 21513965 in words is "twenty-one million, five hundred thirteen thousand, nine hundred sixty-five".