20372561 has 4 divisors (see below), whose sum is σ = 22224624. Its totient is φ = 18520500.

The previous prime is 20372557. The next prime is 20372581. The reversal of 20372561 is 16527302.

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 20372561 - 2² = 20372557 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 20372561.

It is not an unprimeable number, because it can be changed into a prime (20372581) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 926015 + ... + 926036.

It is an arithmetic number, because the mean of its divisors is an integer number (5556156).

Almost surely, 2^20372561 is an apocalyptic number.

It is an amenable number.

20372561 is a deficient number, since it is larger than the sum of its proper divisors (1852063).

20372561 is a wasteful number, since it uses less digits than its factorization.

20372561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1852062.

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

The square root of 20372561 is about 4513.5973457986. The cubic root of 20372561 is about 273.1168798281.

Adding to 20372561 its reverse (16527302), we get a palindrome (36899863).

The spelling of 20372561 in words is "twenty million, three hundred seventy-two thousand, five hundred sixty-one".