21716757 has 24 divisors (see below), whose sum is σ = 32399640. Its totient is φ = 14008320.

The previous prime is 21716749. The next prime is 21716767. The reversal of 21716757 is 75761712.

It can be written as a sum of positive squares in 4 ways, for example, as 9036036 + 12680721 = 3006^2 + 3561^2 .

It is not a de Polignac number, because 21716757 - 2³ = 21716749 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21716767) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 84373 + ... + 84629.

It is an arithmetic number, because the mean of its divisors is an integer number (1349985).

Almost surely, 2^21716757 is an apocalyptic number.

It is an amenable number.

21716757 is a deficient number, since it is larger than the sum of its proper divisors (10682883).

21716757 is a wasteful number, since it uses less digits than its factorization.

21716757 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 533 (or 530 counting only the distinct ones).

The product of its digits is 20580, while the sum is 36.

The square root of 21716757 is about 4660.1241399774. The cubic root of 21716757 is about 278.9962230190.

The spelling of 21716757 in words is "twenty-one million, seven hundred sixteen thousand, seven hundred fifty-seven".