20749657 has 8 divisors (see below), whose sum is σ = 21738240. Its totient is φ = 19768320.

The previous prime is 20749627. The next prime is 20749661. The reversal of 20749657 is 75694702.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20749657 is a prime.

It is a super-3 number, since 3×20749657³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20749627) 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, 4569 + ... + 7897.

It is an arithmetic number, because the mean of its divisors is an integer number (2717280).

Almost surely, 2^20749657 is an apocalyptic number.

It is an amenable number.

20749657 is a deficient number, since it is larger than the sum of its proper divisors (988583).

20749657 is a wasteful number, since it uses less digits than its factorization.

20749657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3623.

The product of its (nonzero) digits is 105840, while the sum is 40.

The square root of 20749657 is about 4555.1791402754. The cubic root of 20749657 is about 274.7917188747.

The spelling of 20749657 in words is "twenty million, seven hundred forty-nine thousand, six hundred fifty-seven".