20778497 has 8 divisors (see below), whose sum is σ = 21489000. Its totient is φ = 20075904.

The previous prime is 20778493. The next prime is 20778517. The reversal of 20778497 is 79487702.

It can be written as a sum of positive squares in 4 ways, for example, as 6270016 + 14508481 = 2504^2 + 3809^2 .

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

It is not a de Polignac number, because 20778497 - 2² = 20778493 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20778493) 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, 3629 + ... + 7397.

It is an arithmetic number, because the mean of its divisors is an integer number (2686125).

Almost surely, 2^20778497 is an apocalyptic number.

It is an amenable number.

20778497 is a deficient number, since it is larger than the sum of its proper divisors (710503).

20778497 is a wasteful number, since it uses less digits than its factorization.

20778497 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3955.

The product of its (nonzero) digits is 197568, while the sum is 44.

The square root of 20778497 is about 4558.3436684831. The cubic root of 20778497 is about 274.9189711685.

The spelling of 20778497 in words is "twenty million, seven hundred seventy-eight thousand, four hundred ninety-seven".