20261021 has 4 divisors (see below), whose sum is σ = 22102944. Its totient is φ = 18419100.

The previous prime is 20261009. The next prime is 20261023. The reversal of 20261021 is 12016202.

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 20261021 - 2¹⁸ = 19998877 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20260987 and 20261005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20261023) 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, 920945 + ... + 920966.

It is an arithmetic number, because the mean of its divisors is an integer number (5525736).

Almost surely, 2^20261021 is an apocalyptic number.

It is an amenable number.

20261021 is a deficient number, since it is larger than the sum of its proper divisors (1841923).

20261021 is a wasteful number, since it uses less digits than its factorization.

20261021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1841922.

The product of its (nonzero) digits is 48, while the sum is 14.

The square root of 20261021 is about 4501.2243889857. The cubic root of 20261021 is about 272.6175280706.

Adding to 20261021 its reverse (12016202), we get a palindrome (32277223).

The spelling of 20261021 in words is "twenty million, two hundred sixty-one thousand, twenty-one".