20723657 has 4 divisors (see below), whose sum is σ = 20850960. Its totient is φ = 20596356.

The previous prime is 20723639. The next prime is 20723669. The reversal of 20723657 is 75632702.

It is a happy number.

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 20723657 - 2⁸ = 20723401 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20723617) 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, 63407 + ... + 63732.

It is an arithmetic number, because the mean of its divisors is an integer number (5212740).

Almost surely, 2^20723657 is an apocalyptic number.

It is an amenable number.

20723657 is a deficient number, since it is larger than the sum of its proper divisors (127303).

20723657 is a wasteful number, since it uses less digits than its factorization.

20723657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 127302.

The product of its (nonzero) digits is 17640, while the sum is 32.

The square root of 20723657 is about 4552.3243513616. The cubic root of 20723657 is about 274.6768965605.

The spelling of 20723657 in words is "twenty million, seven hundred twenty-three thousand, six hundred fifty-seven".