20723651 has 4 divisors (see below), whose sum is σ = 22317792. Its totient is φ = 19129512.

The previous prime is 20723639. The next prime is 20723669. The reversal of 20723651 is 15632702.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20723651 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20723651.

It is not an unprimeable number, because it can be changed into a prime (20723671) 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, 797051 + ... + 797076.

It is an arithmetic number, because the mean of its divisors is an integer number (5579448).

Almost surely, 2^20723651 is an apocalyptic number.

20723651 is a deficient number, since it is larger than the sum of its proper divisors (1594141).

20723651 is a wasteful number, since it uses less digits than its factorization.

20723651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1594140.

The product of its (nonzero) digits is 2520, while the sum is 26.

The square root of 20723651 is about 4552.3236923576. The cubic root of 20723651 is about 274.6768700520.

The spelling of 20723651 in words is "twenty million, seven hundred twenty-three thousand, six hundred fifty-one".