21521349 has 32 divisors (see below), whose sum is σ = 33033600. Its totient is φ = 13841280.

The previous prime is 21521341. The next prime is 21521369. The reversal of 21521349 is 94312512.

It is not a de Polignac number, because 21521349 - 2³ = 21521341 is a prime.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21521341) 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 31 ways as a sum of consecutive naturals, for example, 120142 + ... + 120320.

It is an arithmetic number, because the mean of its divisors is an integer number (1032300).

Almost surely, 2^21521349 is an apocalyptic number.

It is an amenable number.

21521349 is a deficient number, since it is larger than the sum of its proper divisors (11512251).

21521349 is a wasteful number, since it uses less digits than its factorization.

21521349 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 322 (or 316 counting only the distinct ones).

The product of its digits is 2160, while the sum is 27.

The square root of 21521349 is about 4639.1107984182. The cubic root of 21521349 is about 278.1568952017.

The spelling of 21521349 in words is "twenty-one million, five hundred twenty-one thousand, three hundred forty-nine".