21491413 has 12 divisors (see below), whose sum is σ = 23309580. Its totient is φ = 19797696.

The previous prime is 21491411. The next prime is 21491423. The reversal of 21491413 is 31419412.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 20277009 + 1214404 = 4503^2 + 1102^2 .

It is not a de Polignac number, because 21491413 - 2¹ = 21491411 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21491411) 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, 12553 + ... + 14161.

It is an arithmetic number, because the mean of its divisors is an integer number (1942465).

Almost surely, 2^21491413 is an apocalyptic number.

It is an amenable number.

21491413 is a deficient number, since it is larger than the sum of its proper divisors (1818167).

21491413 is a wasteful number, since it uses less digits than its factorization.

21491413 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1684 (or 1665 counting only the distinct ones).

The product of its digits is 864, while the sum is 25.

The square root of 21491413 is about 4635.8831952499. The cubic root of 21491413 is about 278.0278641222.

It can be divided in two parts, 21491 and 413, that added together give a square (21904 = 148²).

The spelling of 21491413 in words is "twenty-one million, four hundred ninety-one thousand, four hundred thirteen".