72651780 has 36 divisors (see below), whose sum is σ = 220377612. Its totient is φ = 19373760.

The previous prime is 72651773. The next prime is 72651781. The reversal of 72651780 is 8715627.

It can be written as a sum of positive squares in 2 ways, for example, as 46457856 + 26193924 = 6816^2 + 5118^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-2 number, since 2×72651780² = 10556562274336800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (72651781) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 201631 + ... + 201990.

Almost surely, 2^72651780 is an apocalyptic number.

It is an amenable number.

72651780 is an abundant number, since it is smaller than the sum of its proper divisors (147725832).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

72651780 is a wasteful number, since it uses less digits than its factorization.

72651780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 403636 (or 403631 counting only the distinct ones).

The product of its (nonzero) digits is 23520, while the sum is 36.

The square root of 72651780 is about 8523.6013515415. The cubic root of 72651780 is about 417.2683261736.

It can be divided in two parts, 7265 and 1780, that added together give a triangular number (9045 = T₁₃₄).

The spelling of 72651780 in words is "seventy-two million, six hundred fifty-one thousand, seven hundred eighty".