21021861445 has 24 divisors (see below), whose sum is σ = 28858783464. Its totient is φ = 14610656256.

The previous prime is 21021861431. The next prime is 21021861449. The reversal of 21021861445 is 54416812012.

It can be written as a sum of positive squares in 12 ways, for example, as 4304147236 + 16717714209 = 65606^2 + 129297^2 .

It is not a de Polignac number, because 21021861445 - 2¹⁵ = 21021828677 is a prime.

It is a super-2 number, since 2×21021861445² (a number of 21 digits) contains 22 as substring.

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 21021861445.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21021861449) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 540754 + ... + 578323.

It is an arithmetic number, because the mean of its divisors is an integer number (1202449311).

Almost surely, 2^21021861445 is an apocalyptic number.

It is an amenable number.

21021861445 is a deficient number, since it is larger than the sum of its proper divisors (7836922019).

21021861445 is a wasteful number, since it uses less digits than its factorization.

21021861445 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1119129 (or 1119112 counting only the distinct ones).

The product of its (nonzero) digits is 15360, while the sum is 34.

The spelling of 21021861445 in words is "twenty-one billion, twenty-one million, eight hundred sixty-one thousand, four hundred forty-five".