20749857 has 4 divisors (see below), whose sum is σ = 27666480. Its totient is φ = 13833236.

The previous prime is 20749837. The next prime is 20749879. The reversal of 20749857 is 75894702.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20749857 - 2⁸ = 20749601 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20749837) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3458307 + ... + 3458312.

It is an arithmetic number, because the mean of its divisors is an integer number (6916620).

Almost surely, 2^20749857 is an apocalyptic number.

It is an amenable number.

20749857 is a deficient number, since it is larger than the sum of its proper divisors (6916623).

20749857 is an equidigital number, since it uses as much as digits as its factorization.

20749857 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6916622.

The product of its (nonzero) digits is 141120, while the sum is 42.

The square root of 20749857 is about 4555.2010932559. The cubic root of 20749857 is about 274.7926017514.

The spelling of 20749857 in words is "twenty million, seven hundred forty-nine thousand, eight hundred fifty-seven".