21661746 has 16 divisors (see below), whose sum is σ = 44721408. Its totient is φ = 6987600.

The previous prime is 21661733. The next prime is 21661781. The reversal of 21661746 is 64716612.

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, 58045 + ... + 58416.

It is an arithmetic number, because the mean of its divisors is an integer number (2795088).

Almost surely, 2^21661746 is an apocalyptic number.

21661746 is an abundant number, since it is smaller than the sum of its proper divisors (23059662).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21661746 is a wasteful number, since it uses less digits than its factorization.

21661746 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 116497.

The product of its digits is 12096, while the sum is 33.

The square root of 21661746 is about 4654.2180868541. The cubic root of 21661746 is about 278.7604475027.

The spelling of 21661746 in words is "twenty-one million, six hundred sixty-one thousand, seven hundred forty-six".