21941661 has 24 divisors (see below), whose sum is σ = 35212320. Its totient is φ = 12103392.

The previous prime is 21941651. The next prime is 21941669. The reversal of 21941661 is 16614912.

It is a happy number.

It is not a de Polignac number, because 21941661 - 2¹⁰ = 21940637 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21941669) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1690 + ... + 6836.

It is an arithmetic number, because the mean of its divisors is an integer number (1467180).

Almost surely, 2^21941661 is an apocalyptic number.

21941661 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21941661 is a deficient number, since it is larger than the sum of its proper divisors (13270659).

21941661 is a wasteful number, since it uses less digits than its factorization.

21941661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5193 (or 5186 counting only the distinct ones).

The product of its digits is 2592, while the sum is 30.

The square root of 21941661 is about 4684.1926732362. The cubic root of 21941661 is about 279.9560347637.

The spelling of 21941661 in words is "twenty-one million, nine hundred forty-one thousand, six hundred sixty-one".