401664643971 has 4 divisors (see below), whose sum is σ = 535552858632. Its totient is φ = 267776429312.

The previous prime is 401664643957. The next prime is 401664643973. The reversal of 401664643971 is 179346466104.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 401664643971 - 2⁹ = 401664643459 is a prime.

It is a super-2 number, since 2×401664643971² (a number of 24 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (401664643973) 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, 66944107326 + ... + 66944107331.

It is an arithmetic number, because the mean of its divisors is an integer number (133888214658).

Almost surely, 2^401664643971 is an apocalyptic number.

401664643971 is a deficient number, since it is larger than the sum of its proper divisors (133888214661).

401664643971 is a wasteful number, since it uses less digits than its factorization.

401664643971 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 133888214660.

The product of its (nonzero) digits is 2612736, while the sum is 51.

The spelling of 401664643971 in words is "four hundred one billion, six hundred sixty-four million, six hundred forty-three thousand, nine hundred seventy-one".