21521493 has 24 divisors (see below), whose sum is σ = 35695296. Its totient is φ = 12240000.

The previous prime is 21521483. The next prime is 21521503. The reversal of 21521493 is 39412512.

It is an interprime number because it is at equal distance from previous prime (21521483) and next prime (21521503).

It is not a de Polignac number, because 21521493 - 2¹⁴ = 21505109 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21521413) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 15133 + ... + 16493.

It is an arithmetic number, because the mean of its divisors is an integer number (1487304).

Almost surely, 2^21521493 is an apocalyptic number.

It is an amenable number.

21521493 is a deficient number, since it is larger than the sum of its proper divisors (14173803).

21521493 is a wasteful number, since it uses less digits than its factorization.

21521493 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1625 (or 1622 counting only the distinct ones).

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

The square root of 21521493 is about 4639.1263186078. The cubic root of 21521493 is about 278.1575155857.

The spelling of 21521493 in words is "twenty-one million, five hundred twenty-one thousand, four hundred ninety-three".