21431552 has 18 divisors (see below), whose sum is σ = 42779898. Its totient is φ = 10715648.

The previous prime is 21431549. The next prime is 21431567. The reversal of 21431552 is 25513412.

It can be written as a sum of positive squares in only one way, i.e., 21381376 + 50176 = 4624^2 + 224^2 .

It is a super-2 number, since 2×21431552² = 918622842257408, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 41603 + ... + 42114.

It is an arithmetic number, because the mean of its divisors is an integer number (2376661).

Almost surely, 2^21431552 is an apocalyptic number.

It is an amenable number.

21431552 is a deficient number, since it is larger than the sum of its proper divisors (21348346).

21431552 is an frugal number, since it uses more digits than its factorization.

21431552 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83733 (or 83719 counting only the distinct ones).

The product of its digits is 1200, while the sum is 23.

The square root of 21431552 is about 4629.4224261780. The cubic root of 21431552 is about 277.7694895779.

Adding to 21431552 its reverse (25513412), we get a palindrome (46944964).

The spelling of 21431552 in words is "twenty-one million, four hundred thirty-one thousand, five hundred fifty-two".