84437721 has 15 divisors (see below), whose sum is σ = 126259023. Its totient is φ = 56236680.

The previous prime is 84437687. The next prime is 84437741. The reversal of 84437721 is 12773448.

It is a happy number.

The square root of 84437721 is 9189.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 49154121 + 35283600 = 7011^2 + 5940^2 .

It is not a de Polignac number, because 84437721 - 2¹³ = 84429529 is a prime.

It is not an unprimeable number, because it can be changed into a prime (84437741) by changing a digit.

It is a polite number, since it can be written in 14 ways as a sum of consecutive naturals, for example, 82191 + ... + 83211.

Almost surely, 2^84437721 is an apocalyptic number.

84437721 is a gapful number since it is divisible by the number (81) formed by its first and last digit.

84437721 is the 9189-th square number.

84437721 is the 4595-th centered octagonal number.

It is an amenable number.

84437721 is a deficient number, since it is larger than the sum of its proper divisors (41821302).

84437721 is an frugal number, since it uses more digits than its factorization.

84437721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2054 (or 1024 counting only the distinct ones).

The product of its digits is 37632, while the sum is 36.

The cubic root of 84437721 is about 438.7113137049.

Multiplying 84437721 by its sum of digits (36), we get a square (3039757956 = 55134²).

It can be divided in two parts, 84437 and 721, that added together give a palindrome (85158).

The spelling of 84437721 in words is "eighty-four million, four hundred thirty-seven thousand, seven hundred twenty-one".