21349637 has 4 divisors (see below), whose sum is σ = 22605516. Its totient is φ = 20093760.

The previous prime is 21349621. The next prime is 21349661. The reversal of 21349637 is 73694312.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 8288641 + 13060996 = 2879^2 + 3614^2 .

It is a cyclic number.

It is not a de Polignac number, because 21349637 - 2⁴ = 21349621 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21349597 and 21349606.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21349667) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 627914 + ... + 627947.

It is an arithmetic number, because the mean of its divisors is an integer number (5651379).

Almost surely, 2^21349637 is an apocalyptic number.

It is an amenable number.

21349637 is a deficient number, since it is larger than the sum of its proper divisors (1255879).

21349637 is a wasteful number, since it uses less digits than its factorization.

21349637 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1255878.

The product of its digits is 27216, while the sum is 35.

The square root of 21349637 is about 4620.5667401305. The cubic root of 21349637 is about 277.4151438190.

The spelling of 21349637 in words is "twenty-one million, three hundred forty-nine thousand, six hundred thirty-seven".