70721557 has 4 divisors (see below), whose sum is σ = 72055980. Its totient is φ = 69387136.

The previous prime is 70721531. The next prime is 70721593. The reversal of 70721557 is 75512707.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 75512707 = 19 ⋅3974353.

It can be written as a sum of positive squares in 2 ways, for example, as 22363441 + 48358116 = 4729^2 + 6954^2 .

It is a cyclic number.

It is not a de Polignac number, because 70721557 - 2⁷ = 70721429 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (70721507) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 667132 + ... + 667237.

It is an arithmetic number, because the mean of its divisors is an integer number (18013995).

Almost surely, 2^70721557 is an apocalyptic number.

It is an amenable number.

70721557 is a deficient number, since it is larger than the sum of its proper divisors (1334423).

70721557 is a wasteful number, since it uses less digits than its factorization.

70721557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1334422.

The product of its (nonzero) digits is 17150, while the sum is 34.

The square root of 70721557 is about 8409.6109898140. The cubic root of 70721557 is about 413.5397598072.

The spelling of 70721557 in words is "seventy million, seven hundred twenty-one thousand, five hundred fifty-seven".