21049665457 has 8 divisors (see below), whose sum is σ = 21793242240. Its totient is φ = 20307270480.

The previous prime is 21049665443. The next prime is 21049665479. The reversal of 21049665457 is 75456694012.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21049665457 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21049665457.

It is not an unprimeable number, because it can be changed into a prime (21049662457) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 259123 + ... + 330520.

It is an arithmetic number, because the mean of its divisors is an integer number (2724155280).

Almost surely, 2^21049665457 is an apocalyptic number.

It is an amenable number.

21049665457 is a deficient number, since it is larger than the sum of its proper divisors (743576783).

21049665457 is a wasteful number, since it uses less digits than its factorization.

21049665457 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 590903.

The product of its (nonzero) digits is 1814400, while the sum is 49.

The spelling of 21049665457 in words is "twenty-one billion, forty-nine million, six hundred sixty-five thousand, four hundred fifty-seven".