21901766 has 8 divisors (see below), whose sum is σ = 32911320. Its totient is φ = 10931328.

The previous prime is 21901753. The next prime is 21901769. The reversal of 21901766 is 66710912.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-3 number, since 3×21901766³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21901769) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8336 + ... + 10643.

It is an arithmetic number, because the mean of its divisors is an integer number (4113915).

Almost surely, 2^21901766 is an apocalyptic number.

21901766 is a deficient number, since it is larger than the sum of its proper divisors (11009554).

21901766 is a wasteful number, since it uses less digits than its factorization.

21901766 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19558.

The product of its (nonzero) digits is 4536, while the sum is 32.

The square root of 21901766 is about 4679.9322644671. The cubic root of 21901766 is about 279.7862569449.

The spelling of 21901766 in words is "twenty-one million, nine hundred one thousand, seven hundred sixty-six".