70721731 has 2 divisors, whose sum is σ = 70721732. Its totient is φ = 70721730.

The previous prime is 70721719. The next prime is 70721737. The reversal of 70721731 is 13712707.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 70721731 - 2⁷ = 70721603 is a prime.

It is a super-2 number, since 2×70721731² = 10003126471272722, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 70721731.

It is not a weakly prime, because it can be changed into another prime (70721737) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 35360865 + 35360866.

It is an arithmetic number, because the mean of its divisors is an integer number (35360866).

Almost surely, 2^70721731 is an apocalyptic number.

70721731 is a deficient number, since it is larger than the sum of its proper divisors (1).

70721731 is an equidigital number, since it uses as much as digits as its factorization.

70721731 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2058, while the sum is 28.

The square root of 70721731 is about 8409.6213351137. The cubic root of 70721731 is about 413.5400989582.

It can be divided in two parts, 70 and 721731, that added together give a triangular number (721801 = T₁₂₀₁).

The spelling of 70721731 in words is "seventy million, seven hundred twenty-one thousand, seven hundred thirty-one".