21485421 has 6 divisors (see below), whose sum is σ = 31034510. Its totient is φ = 14323608.

The previous prime is 21485413. The next prime is 21485437. The reversal of 21485421 is 12458412.

It can be written as a sum of positive squares in only one way, i.e., 14356521 + 7128900 = 3789^2 + 2670^2 .

It is not a de Polignac number, because 21485421 - 2³ = 21485413 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 (21485021) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1193626 + ... + 1193643.

Almost surely, 2^21485421 is an apocalyptic number.

It is an amenable number.

21485421 is a deficient number, since it is larger than the sum of its proper divisors (9549089).

21485421 is a wasteful number, since it uses less digits than its factorization.

21485421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2387275 (or 2387272 counting only the distinct ones).

The product of its digits is 2560, while the sum is 27.

The square root of 21485421 is about 4635.2368871504. The cubic root of 21485421 is about 278.0020228274.

It can be divided in two parts, 2148 and 5421, that added together give a square (7569 = 87²).

The spelling of 21485421 in words is "twenty-one million, four hundred eighty-five thousand, four hundred twenty-one".