20251621 has 8 divisors (see below), whose sum is σ = 22135904. Its totient is φ = 18414000.

The previous prime is 20251619. The next prime is 20251631. The reversal of 20251621 is 12615202.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20251621 - 2¹ = 20251619 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 (20251601) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10755 + ... + 12496.

It is an arithmetic number, because the mean of its divisors is an integer number (2766988).

Almost surely, 2^20251621 is an apocalyptic number.

It is an amenable number.

20251621 is a deficient number, since it is larger than the sum of its proper divisors (1884283).

20251621 is a wasteful number, since it uses less digits than its factorization.

20251621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23331.

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 20251621 is about 4500.1801075068. The cubic root of 20251621 is about 272.5753616999.

Adding to 20251621 its reverse (12615202), we get a palindrome (32866823).

The spelling of 20251621 in words is "twenty million, two hundred fifty-one thousand, six hundred twenty-one".