20256621 has 16 divisors (see below), whose sum is σ = 33673728. Its totient is φ = 10522800.

The previous prime is 20256619. The next prime is 20256631. The reversal of 20256621 is 12665202.

It is not a de Polignac number, because 20256621 - 2¹ = 20256619 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20256591 and 20256600.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20256631) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 43615 + ... + 44076.

It is an arithmetic number, because the mean of its divisors is an integer number (2104608).

Almost surely, 2^20256621 is an apocalyptic number.

20256621 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

20256621 is a deficient number, since it is larger than the sum of its proper divisors (13417107).

20256621 is a wasteful number, since it uses less digits than its factorization.

20256621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87712.

The product of its (nonzero) digits is 1440, while the sum is 24.

The square root of 20256621 is about 4500.7356065426. The cubic root of 20256621 is about 272.5977922444.

It can be divided in two parts, 2025 and 6621, that added together give a triangular number (8646 = T₁₃₁).

The spelling of 20256621 in words is "twenty million, two hundred fifty-six thousand, six hundred twenty-one".