40155721 has 4 divisors (see below), whose sum is σ = 42269200. Its totient is φ = 38042244.

The previous prime is 40155701. The next prime is 40155737. The reversal of 40155721 is 12755104.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 40155721 - 2⁹ = 40155209 is a prime.

It is a super-2 number, since 2×40155721² = 3224963858059682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (40155701) 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, 1056711 + ... + 1056748.

It is an arithmetic number, because the mean of its divisors is an integer number (10567300).

Almost surely, 2^40155721 is an apocalyptic number.

It is an amenable number.

40155721 is a deficient number, since it is larger than the sum of its proper divisors (2113479).

40155721 is a wasteful number, since it uses less digits than its factorization.

40155721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2113478.

The product of its (nonzero) digits is 1400, while the sum is 25.

The square root of 40155721 is about 6336.8541880021. The cubic root of 40155721 is about 342.4384132786.

The spelling of 40155721 in words is "forty million, one hundred fifty-five thousand, seven hundred twenty-one".