40097991 has 4 divisors (see below), whose sum is σ = 53463992. Its totient is φ = 26731992.

The previous prime is 40097983. The next prime is 40098001. The reversal of 40097991 is 19979004.

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

It is not a de Polignac number, because 40097991 - 2³ = 40097983 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (40097791) 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, 6682996 + ... + 6683001.

It is an arithmetic number, because the mean of its divisors is an integer number (13365998).

Almost surely, 2^40097991 is an apocalyptic number.

40097991 is a deficient number, since it is larger than the sum of its proper divisors (13366001).

40097991 is a wasteful number, since it uses less digits than its factorization.

40097991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13366000.

The product of its (nonzero) digits is 20412, while the sum is 39.

The square root of 40097991 is about 6332.2974503730. The cubic root of 40097991 is about 342.2742320170.

Adding to 40097991 its product of nonzero digits (20412), we get a triangular number (40118403 = T₈₉₅₇).

The spelling of 40097991 in words is "forty million, ninety-seven thousand, nine hundred ninety-one".