21057772 has 6 divisors (see below), whose sum is σ = 36851108. Its totient is φ = 10528884.

The previous prime is 21057769. The next prime is 21057779. The reversal of 21057772 is 27775012.

It is not an unprimeable number, because it can be changed into a prime (21057779) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2632218 + ... + 2632225.

Almost surely, 2^21057772 is an apocalyptic number.

It is an amenable number.

21057772 is a deficient number, since it is larger than the sum of its proper divisors (15793336).

21057772 is a wasteful number, since it uses less digits than its factorization.

21057772 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5264447 (or 5264445 counting only the distinct ones).

The product of its (nonzero) digits is 6860, while the sum is 31.

The square root of 21057772 is about 4588.8748076190. The cubic root of 21057772 is about 276.1451837153.

The spelling of 21057772 in words is "twenty-one million, fifty-seven thousand, seven hundred seventy-two".