21065757 has 8 divisors (see below), whose sum is σ = 28233984. Its totient is φ = 13970688.

The previous prime is 21065753. The next prime is 21065767. The reversal of 21065757 is 75756012.

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

It is not a de Polignac number, because 21065757 - 2² = 21065753 is a prime.

It is a super-2 number, since 2×21065757² = 887532235966098, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21065753) 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, 17613 + ... + 18770.

It is an arithmetic number, because the mean of its divisors is an integer number (3529248).

Almost surely, 2^21065757 is an apocalyptic number.

It is an amenable number.

21065757 is a deficient number, since it is larger than the sum of its proper divisors (7168227).

21065757 is a wasteful number, since it uses less digits than its factorization.

21065757 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36579.

The product of its (nonzero) digits is 14700, while the sum is 33.

The square root of 21065757 is about 4589.7447641454. The cubic root of 21065757 is about 276.1800835873.

The spelling of 21065757 in words is "twenty-one million, sixty-five thousand, seven hundred fifty-seven".