21906494 has 4 divisors (see below), whose sum is σ = 32859744. Its totient is φ = 10953246.

The previous prime is 21906481. The next prime is 21906499. The reversal of 21906494 is 49460912.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21906499) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5476622 + ... + 5476625.

It is an arithmetic number, because the mean of its divisors is an integer number (8214936).

Almost surely, 2^21906494 is an apocalyptic number.

21906494 is a deficient number, since it is larger than the sum of its proper divisors (10953250).

21906494 is a wasteful number, since it uses less digits than its factorization.

21906494 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10953249.

The product of its (nonzero) digits is 15552, while the sum is 35.

The square root of 21906494 is about 4680.4373727249. The cubic root of 21906494 is about 279.8063882629.

The spelling of 21906494 in words is "twenty-one million, nine hundred six thousand, four hundred ninety-four".