21154769 has 4 divisors (see below), whose sum is σ = 21245796. Its totient is φ = 21063744.

The previous prime is 21154759. The next prime is 21154789. The reversal of 21154769 is 96745112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1926544 + 19228225 = 1388^2 + 4385^2 .

It is a cyclic number.

It is not a de Polignac number, because 21154769 - 2¹² = 21150673 is a prime.

It is a super-2 number, since 2×21154769² = 895048502886722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21154709) 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, 45164 + ... + 45629.

It is an arithmetic number, because the mean of its divisors is an integer number (5311449).

Almost surely, 2^21154769 is an apocalyptic number.

It is an amenable number.

21154769 is a deficient number, since it is larger than the sum of its proper divisors (91027).

21154769 is an equidigital number, since it uses as much as digits as its factorization.

21154769 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91026.

The product of its digits is 15120, while the sum is 35.

The square root of 21154769 is about 4599.4313778988. The cubic root of 21154769 is about 276.5685307015.

The spelling of 21154769 in words is "twenty-one million, one hundred fifty-four thousand, seven hundred sixty-nine".