21908312 has 8 divisors (see below), whose sum is σ = 41078100. Its totient is φ = 10954152.

The previous prime is 21908303. The next prime is 21908317. The reversal of 21908312 is 21380912.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21908317) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1369262 + ... + 1369277.

Almost surely, 2^21908312 is an apocalyptic number.

It is an amenable number.

21908312 is a deficient number, since it is larger than the sum of its proper divisors (19169788).

21908312 is a wasteful number, since it uses less digits than its factorization.

21908312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2738545 (or 2738541 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 26.

The square root of 21908312 is about 4680.6315813146. The cubic root of 21908312 is about 279.8141283413.

The spelling of 21908312 in words is "twenty-one million, nine hundred eight thousand, three hundred twelve".