21021431444 has 24 divisors (see below), whose sum is σ = 39626311368. Its totient is φ = 9699995520.

The previous prime is 21021431443. The next prime is 21021431449. The reversal of 21021431444 is 44413412012.

It can be written as a sum of positive squares in 4 ways, for example, as 1717107844 + 19304323600 = 41438^2 + 138940^2 .

It is a Harshad number since it is a multiple of its sum of digits (26).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21021431443) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 197534 + ... + 284714.

It is an arithmetic number, because the mean of its divisors is an integer number (1651096307).

Almost surely, 2^21021431444 is an apocalyptic number.

It is an amenable number.

21021431444 is a deficient number, since it is larger than the sum of its proper divisors (18604879924).

21021431444 is a wasteful number, since it uses less digits than its factorization.

21021431444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91835 (or 91833 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 26.

Adding to 21021431444 its reverse (44413412012), we get a palindrome (65434843456).

The spelling of 21021431444 in words is "twenty-one billion, twenty-one million, four hundred thirty-one thousand, four hundred forty-four".