21661774 has 16 divisors (see below), whose sum is σ = 34570368. Its totient is φ = 10144512.

The previous prime is 21661733. The next prime is 21661781. The reversal of 21661774 is 47716612.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (34).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6154 + ... + 9010.

It is an arithmetic number, because the mean of its divisors is an integer number (2160648).

Almost surely, 2^21661774 is an apocalyptic number.

21661774 is a deficient number, since it is larger than the sum of its proper divisors (12908594).

21661774 is a wasteful number, since it uses less digits than its factorization.

21661774 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3099.

The product of its digits is 14112, while the sum is 34.

The square root of 21661774 is about 4654.2210948772. The cubic root of 21661774 is about 278.7605676113.

The spelling of 21661774 in words is "twenty-one million, six hundred sixty-one thousand, seven hundred seventy-four".