21453634 has 4 divisors (see below), whose sum is σ = 32180454. Its totient is φ = 10726816.

The previous prime is 21453623. The next prime is 21453637. The reversal of 21453634 is 43635412.

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

It can be written as a sum of positive squares in only one way, i.e., 18020025 + 3433609 = 4245^2 + 1853^2 .

It is not an unprimeable number, because it can be changed into a prime (21453637) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5363407 + ... + 5363410.

Almost surely, 2^21453634 is an apocalyptic number.

21453634 is a deficient number, since it is larger than the sum of its proper divisors (10726820).

21453634 is a wasteful number, since it uses less digits than its factorization.

21453634 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10726819.

The product of its digits is 8640, while the sum is 28.

The square root of 21453634 is about 4631.8067748990. The cubic root of 21453634 is about 277.8648567644.

The spelling of 21453634 in words is "twenty-one million, four hundred fifty-three thousand, six hundred thirty-four".