21850661 has 16 divisors (see below), whose sum is σ = 26651520. Its totient is φ = 17487360.

The previous prime is 21850637. The next prime is 21850679. The reversal of 21850661 is 16605812.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21850661 - 2⁶ = 21850597 is a prime.

It is a super-2 number, since 2×21850661² = 954902772273842, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21850061) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15881 + ... + 17201.

It is an arithmetic number, because the mean of its divisors is an integer number (1665720).

Almost surely, 2^21850661 is an apocalyptic number.

It is an amenable number.

21850661 is a deficient number, since it is larger than the sum of its proper divisors (4800859).

21850661 is a wasteful number, since it uses less digits than its factorization.

21850661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1484.

The product of its (nonzero) digits is 2880, while the sum is 29.

The square root of 21850661 is about 4674.4690607597. The cubic root of 21850661 is about 279.5684721884.

The spelling of 21850661 in words is "twenty-one million, eight hundred fifty thousand, six hundred sixty-one".