21217692 has 12 divisors (see below), whose sum is σ = 49507976. Its totient is φ = 7072560.

The previous prime is 21217681. The next prime is 21217697. The reversal of 21217692 is 29671212.

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21217697) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 884059 + ... + 884082.

Almost surely, 2^21217692 is an apocalyptic number.

It is an amenable number.

21217692 is an abundant number, since it is smaller than the sum of its proper divisors (28290284).

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

21217692 is a wasteful number, since it uses less digits than its factorization.

21217692 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1768148 (or 1768146 counting only the distinct ones).

The product of its digits is 3024, while the sum is 30.

The square root of 21217692 is about 4606.2666010556. The cubic root of 21217692 is about 276.8424688699.

The spelling of 21217692 in words is "twenty-one million, two hundred seventeen thousand, six hundred ninety-two".