21521259 has 12 divisors (see below), whose sum is σ = 31480800. Its totient is φ = 14165424.

The previous prime is 21521257. The next prime is 21521263. The reversal of 21521259 is 95212512.

It is not a de Polignac number, because 21521259 - 2¹ = 21521257 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21521251) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 14424 + ... + 15845.

It is an arithmetic number, because the mean of its divisors is an integer number (2623400).

Almost surely, 2^21521259 is an apocalyptic number.

21521259 is a deficient number, since it is larger than the sum of its proper divisors (9959541).

21521259 is a wasteful number, since it uses less digits than its factorization.

21521259 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30354 (or 30351 counting only the distinct ones).

The product of its digits is 1800, while the sum is 27.

The square root of 21521259 is about 4639.1010982732. The cubic root of 21521259 is about 278.1565074603.

The spelling of 21521259 in words is "twenty-one million, five hundred twenty-one thousand, two hundred fifty-nine".