21980397 has 8 divisors (see below), whose sum is σ = 30849760. Its totient is φ = 13882320.

The previous prime is 21980389. The next prime is 21980401. The reversal of 21980397 is 79308912.

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

It is not a de Polignac number, because 21980397 - 2³ = 21980389 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21980317) 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, 192754 + ... + 192867.

It is an arithmetic number, because the mean of its divisors is an integer number (3856220).

Almost surely, 2^21980397 is an apocalyptic number.

It is an amenable number.

21980397 is a deficient number, since it is larger than the sum of its proper divisors (8869363).

21980397 is a wasteful number, since it uses less digits than its factorization.

21980397 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 385643.

The product of its (nonzero) digits is 27216, while the sum is 39.

The square root of 21980397 is about 4688.3256072931. The cubic root of 21980397 is about 280.1206835206.

The spelling of 21980397 in words is "twenty-one million, nine hundred eighty thousand, three hundred ninety-seven".