21478757 has 8 divisors (see below), whose sum is σ = 22698240. Its totient is φ = 20283120.

The previous prime is 21478741. The next prime is 21478781. The reversal of 21478757 is 75787412.

21478757 = 324² + 325² + ... + 461².

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

It is a cyclic number.

It is not a de Polignac number, because 21478757 - 2⁴ = 21478741 is a prime.

It is a super-2 number, since 2×21478757² = 922674004530098, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21478057) 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, 4094 + ... + 7727.

It is an arithmetic number, because the mean of its divisors is an integer number (2837280).

Almost surely, 2^21478757 is an apocalyptic number.

It is an amenable number.

21478757 is a deficient number, since it is larger than the sum of its proper divisors (1219483).

21478757 is a wasteful number, since it uses less digits than its factorization.

21478757 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11923.

The product of its digits is 109760, while the sum is 41.

The square root of 21478757 is about 4634.5179900395. The cubic root of 21478757 is about 277.9732778000.

The spelling of 21478757 in words is "twenty-one million, four hundred seventy-eight thousand, seven hundred fifty-seven".