20899621 has 4 divisors (see below), whose sum is σ = 20948544. Its totient is φ = 20850700.

The previous prime is 20899607. The next prime is 20899679. The reversal of 20899621 is 12699802.

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 20899621 - 2⁵ = 20899589 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20899121) 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, 23815 + ... + 24676.

It is an arithmetic number, because the mean of its divisors is an integer number (5237136).

Almost surely, 2^20899621 is an apocalyptic number.

It is an amenable number.

20899621 is a deficient number, since it is larger than the sum of its proper divisors (48923).

20899621 is an equidigital number, since it uses as much as digits as its factorization.

20899621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48922.

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

The square root of 20899621 is about 4571.6103289760. The cubic root of 20899621 is about 275.4521311689.

The spelling of 20899621 in words is "twenty million, eight hundred ninety-nine thousand, six hundred twenty-one".