21797951 has 8 divisors (see below), whose sum is σ = 25995264. Its totient is φ = 17871480.

The previous prime is 21797939. The next prime is 21797953. The reversal of 21797951 is 15979712.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21797951 - 2¹⁰ = 21796927 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21797899 and 21797908.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21797953) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 67535 + ... + 67856.

It is an arithmetic number, because the mean of its divisors is an integer number (3249408).

Almost surely, 2^21797951 is an apocalyptic number.

21797951 is a deficient number, since it is larger than the sum of its proper divisors (4197313).

21797951 is a wasteful number, since it uses less digits than its factorization.

21797951 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 135421.

The product of its digits is 39690, while the sum is 41.

The square root of 21797951 is about 4668.8275830234. The cubic root of 21797951 is about 279.3434916678.

The spelling of 21797951 in words is "twenty-one million, seven hundred ninety-seven thousand, nine hundred fifty-one".