20778457 has 8 divisors (see below), whose sum is σ = 24996800. Its totient is φ = 16872624.

The previous prime is 20778449. The next prime is 20778473. The reversal of 20778457 is 75487702.

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 20778457 - 2³ = 20778449 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20778487) 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, 77982 + ... + 78247.

It is an arithmetic number, because the mean of its divisors is an integer number (3124600).

Almost surely, 2^20778457 is an apocalyptic number.

It is an amenable number.

20778457 is a deficient number, since it is larger than the sum of its proper divisors (4218343).

20778457 is a wasteful number, since it uses less digits than its factorization.

20778457 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 156255.

The product of its (nonzero) digits is 109760, while the sum is 40.

The square root of 20778457 is about 4558.3392809224. The cubic root of 20778457 is about 274.9187947559.

The spelling of 20778457 in words is "twenty million, seven hundred seventy-eight thousand, four hundred fifty-seven".