71220021 has 16 divisors (see below), whose sum is σ = 102254400. Its totient is φ = 43927808.

The previous prime is 71220013. The next prime is 71220043. The reversal of 71220021 is 12002217.

It is a cyclic number.

It is not a de Polignac number, because 71220021 - 2³ = 71220013 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (71220091) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8826 + ... + 14843.

It is an arithmetic number, because the mean of its divisors is an integer number (6390900).

Almost surely, 2^71220021 is an apocalyptic number.

It is an amenable number.

71220021 is a deficient number, since it is larger than the sum of its proper divisors (31034379).

71220021 is a wasteful number, since it uses less digits than its factorization.

71220021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23748.

The product of its (nonzero) digits is 56, while the sum is 15.

The square root of 71220021 is about 8439.1955185314. The cubic root of 71220021 is about 414.5090647925.

Adding to 71220021 its reverse (12002217), we get a palindrome (83222238).

It can be divided in two parts, 712200 and 21, that added together give a triangular number (712221 = T₁₁₉₃).

The spelling of 71220021 in words is "seventy-one million, two hundred twenty thousand, twenty-one".