400158721 has 4 divisors (see below), whose sum is σ = 402844500. Its totient is φ = 397472944.

The previous prime is 400158691. The next prime is 400158727. The reversal of 400158721 is 127851004.

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

It can be written as a sum of positive squares in 2 ways, for example, as 96040000 + 304118721 = 9800^2 + 17439^2 .

It is a cyclic number.

It is not a de Polignac number, because 400158721 - 2⁷ = 400158593 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 400158721.

It is not an unprimeable number, because it can be changed into a prime (400158727) 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, 1342666 + ... + 1342963.

It is an arithmetic number, because the mean of its divisors is an integer number (100711125).

Almost surely, 2^400158721 is an apocalyptic number.

It is an amenable number.

400158721 is a deficient number, since it is larger than the sum of its proper divisors (2685779).

400158721 is a wasteful number, since it uses less digits than its factorization.

400158721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2685778.

The product of its (nonzero) digits is 2240, while the sum is 28.

The square root of 400158721 is about 20003.9676314475. The cubic root of 400158721 is about 736.9037423680.

The spelling of 400158721 in words is "four hundred million, one hundred fifty-eight thousand, seven hundred twenty-one".