73218406921 has 27 divisors (see below), whose sum is σ = 85551438567. Its totient is φ = 62603471040.

The previous prime is 73218406867. The next prime is 73218406951. The reversal of 73218406921 is 12960481237.

The square root of 73218406921 is 270589.

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., 57003950025 + 16214456896 = 238755^2 + 127336^2 .

It is not a de Polignac number, because 73218406921 - 2¹⁵ = 73218374153 is a prime.

It is a super-2 number, since 2×73218406921² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (73218406951) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 50599420 + ... + 50600866.

Almost surely, 2^73218406921 is an apocalyptic number.

73218406921 is the 270589-th square number.

73218406921 is the 135295-th centered octagonal number.

It is an amenable number.

73218406921 is a deficient number, since it is larger than the sum of its proper divisors (12333031646).

73218406921 is an equidigital number, since it uses as much as digits as its factorization.

73218406921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2950 (or 1475 counting only the distinct ones).

The product of its (nonzero) digits is 145152, while the sum is 43.

The spelling of 73218406921 in words is "seventy-three billion, two hundred eighteen million, four hundred six thousand, nine hundred twenty-one".