21253064761 has 4 divisors (see below), whose sum is σ = 21256932352. Its totient is φ = 21249197172.

The previous prime is 21253064759. The next prime is 21253064771. The reversal of 21253064761 is 16746035212.

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 21253064761 - 2¹ = 21253064759 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21253064761.

It is not an unprimeable number, because it can be changed into a prime (21253064731) 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, 1925541 + ... + 1936546.

It is an arithmetic number, because the mean of its divisors is an integer number (5314233088).

Almost surely, 2^21253064761 is an apocalyptic number.

It is an amenable number.

21253064761 is a deficient number, since it is larger than the sum of its proper divisors (3867591).

21253064761 is an equidigital number, since it uses as much as digits as its factorization.

21253064761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3867590.

The product of its (nonzero) digits is 60480, while the sum is 37.

Adding to 21253064761 its reverse (16746035212), we get a palindrome (37999099973).

The spelling of 21253064761 in words is "twenty-one billion, two hundred fifty-three million, sixty-four thousand, seven hundred sixty-one".