20621899 has 4 divisors (see below), whose sum is σ = 20637760. Its totient is φ = 20606040.

The previous prime is 20621891. The next prime is 20621903. The reversal of 20621899 is 99812602.

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

It is a cyclic number.

It is not a de Polignac number, because 20621899 - 2³ = 20621891 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20621891) 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, 5787 + ... + 8644.

It is an arithmetic number, because the mean of its divisors is an integer number (5159440).

Almost surely, 2^20621899 is an apocalyptic number.

20621899 is a deficient number, since it is larger than the sum of its proper divisors (15861).

20621899 is a wasteful number, since it uses less digits than its factorization.

20621899 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15860.

The product of its (nonzero) digits is 15552, while the sum is 37.

The square root of 20621899 is about 4541.1341094489. The cubic root of 20621899 is about 274.2265827832.

The spelling of 20621899 in words is "twenty million, six hundred twenty-one thousand, eight hundred ninety-nine".