21023761 has 4 divisors (see below), whose sum is σ = 22935024. Its totient is φ = 19112500.

The previous prime is 21023759. The next prime is 21023767. The reversal of 21023761 is 16732012.

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 not a de Polignac number, because 21023761 - 2¹ = 21023759 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21023767) 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, 955615 + ... + 955636.

It is an arithmetic number, because the mean of its divisors is an integer number (5733756).

Almost surely, 2^21023761 is an apocalyptic number.

It is an amenable number.

21023761 is a deficient number, since it is larger than the sum of its proper divisors (1911263).

21023761 is a wasteful number, since it uses less digits than its factorization.

21023761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1911262.

The product of its (nonzero) digits is 504, while the sum is 22.

The square root of 21023761 is about 4585.1674996667. The cubic root of 21023761 is about 275.9964336513.

Adding to 21023761 its reverse (16732012), we get a palindrome (37755773).

The spelling of 21023761 in words is "twenty-one million, twenty-three thousand, seven hundred sixty-one".