21452013661 has 16 divisors (see below), whose sum is σ = 24544724400. Its totient is φ = 18602293248.

The previous prime is 21452013647. The next prime is 21452013697. The reversal of 21452013661 is 16631025412.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 3621752761 + 17830260900 = 60181^2 + 133530^2 .

It is a cyclic number.

It is not a de Polignac number, because 21452013661 - 2¹⁷ = 21451882589 is a prime.

It is a super-2 number, since 2×21452013661² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21452017661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 754996 + ... + 782893.

It is an arithmetic number, because the mean of its divisors is an integer number (1534045275).

Almost surely, 2^21452013661 is an apocalyptic number.

It is an amenable number.

21452013661 is a deficient number, since it is larger than the sum of its proper divisors (3092710739).

21452013661 is a wasteful number, since it uses less digits than its factorization.

21452013661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1537968.

The product of its (nonzero) digits is 8640, while the sum is 31.

The spelling of 21452013661 in words is "twenty-one billion, four hundred fifty-two million, thirteen thousand, six hundred sixty-one".