21421773 has 8 divisors (see below), whose sum is σ = 31736000. Its totient is φ = 14281164.

The previous prime is 21421769. The next prime is 21421793. The reversal of 21421773 is 37712412.

It is a happy number.

It is not a de Polignac number, because 21421773 - 2² = 21421769 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 793399 = 21421773 / (2 + 1 + 4 + 2 + 1 + 7 + 7 + 3).

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21421703) 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, 396673 + ... + 396726.

It is an arithmetic number, because the mean of its divisors is an integer number (3967000).

Almost surely, 2^21421773 is an apocalyptic number.

It is an amenable number.

21421773 is a deficient number, since it is larger than the sum of its proper divisors (10314227).

21421773 is an equidigital number, since it uses as much as digits as its factorization.

21421773 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 793408 (or 793402 counting only the distinct ones).

The product of its digits is 2352, while the sum is 27.

The square root of 21421773 is about 4628.3661263993. The cubic root of 21421773 is about 277.7272353494.

The spelling of 21421773 in words is "twenty-one million, four hundred twenty-one thousand, seven hundred seventy-three".