78211971 has 24 divisors (see below), whose sum is σ = 114841584. Its totient is φ = 51287040.

The previous prime is 78211963. The next prime is 78211997. The reversal of 78211971 is 17911287.

It is not a de Polignac number, because 78211971 - 2³ = 78211963 is a prime.

It is a super-2 number, since 2×78211971² = 12234224815409682, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78211921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 231915 + ... + 232251.

It is an arithmetic number, because the mean of its divisors is an integer number (4785066).

Almost surely, 2^78211971 is an apocalyptic number.

78211971 is a deficient number, since it is larger than the sum of its proper divisors (36629613).

78211971 is a wasteful number, since it uses less digits than its factorization.

78211971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 691 (or 688 counting only the distinct ones).

The product of its digits is 7056, while the sum is 36.

The square root of 78211971 is about 8843.7532190807. The cubic root of 78211971 is about 427.6525607133.

The spelling of 78211971 in words is "seventy-eight million, two hundred eleven thousand, nine hundred seventy-one".