21385634 has 4 divisors (see below), whose sum is σ = 32078454. Its totient is φ = 10692816.

The previous prime is 21385633. The next prime is 21385649. The reversal of 21385634 is 43658312.

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., 21187609 + 198025 = 4603^2 + 445^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21385634.

It is not an unprimeable number, because it can be changed into a prime (21385633) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5346407 + ... + 5346410.

Almost surely, 2^21385634 is an apocalyptic number.

21385634 is a deficient number, since it is larger than the sum of its proper divisors (10692820).

21385634 is a wasteful number, since it uses less digits than its factorization.

21385634 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10692819.

The product of its digits is 17280, while the sum is 32.

The square root of 21385634 is about 4624.4604009549. The cubic root of 21385634 is about 277.5709701335.

The spelling of 21385634 in words is "twenty-one million, three hundred eighty-five thousand, six hundred thirty-four".