21661797 has 8 divisors (see below), whose sum is σ = 29009440. Its totient is φ = 14377680.

The previous prime is 21661793. The next prime is 21661807. The reversal of 21661797 is 79716612.

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

It is not a de Polignac number, because 21661797 - 2² = 21661793 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 (21661793) 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, 15079 + ... + 16452.

It is an arithmetic number, because the mean of its divisors is an integer number (3626180).

Almost surely, 2^21661797 is an apocalyptic number.

It is an amenable number.

21661797 is a deficient number, since it is larger than the sum of its proper divisors (7347643).

21661797 is a wasteful number, since it uses less digits than its factorization.

21661797 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31763.

The product of its digits is 31752, while the sum is 39.

The square root of 21661797 is about 4654.2235657519. The cubic root of 21661797 is about 278.7606662719.

The spelling of 21661797 in words is "twenty-one million, six hundred sixty-one thousand, seven hundred ninety-seven".