21513373 has 8 divisors (see below), whose sum is σ = 25158848. Its totient is φ = 18010944.

The previous prime is 21513361. The next prime is 21513383. The reversal of 21513373 is 37331512.

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

It is not a de Polignac number, because 21513373 - 2⁹ = 21512861 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 (21513383) 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, 35436 + ... + 36037.

It is an arithmetic number, because the mean of its divisors is an integer number (3144856).

Almost surely, 2^21513373 is an apocalyptic number.

It is an amenable number.

21513373 is a deficient number, since it is larger than the sum of its proper divisors (3645475).

21513373 is an equidigital number, since it uses as much as digits as its factorization.

21513373 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71523.

The product of its digits is 1890, while the sum is 25.

The square root of 21513373 is about 4638.2510712552. The cubic root of 21513373 is about 278.1225284972.

Adding to 21513373 its reverse (37331512), we get a palindrome (58844885).

The spelling of 21513373 in words is "twenty-one million, five hundred thirteen thousand, three hundred seventy-three".