21497678 has 8 divisors (see below), whose sum is σ = 32996568. Its totient is φ = 10498824.

The previous prime is 21497677. The next prime is 21497689. The reversal of 21497678 is 87679412.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21497677) 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, 124901 + ... + 125072.

It is an arithmetic number, because the mean of its divisors is an integer number (4124571).

Almost surely, 2^21497678 is an apocalyptic number.

21497678 is a deficient number, since it is larger than the sum of its proper divisors (11498890).

21497678 is a wasteful number, since it uses less digits than its factorization.

21497678 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 250018.

The product of its digits is 169344, while the sum is 44.

The square root of 21497678 is about 4636.5588532876. The cubic root of 21497678 is about 278.0548776297.

The spelling of 21497678 in words is "twenty-one million, four hundred ninety-seven thousand, six hundred seventy-eight".