40001556 has 48 divisors (see below), whose sum is σ = 110355840. Its totient is φ = 11034240.

The previous prime is 40001519. The next prime is 40001557. The reversal of 40001556 is 65510004.

It is a happy number.

It is a super-2 number, since 2×40001556² = 3200248964842272, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (40001557) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5775 + ... + 10646.

It is an arithmetic number, because the mean of its divisors is an integer number (2299080).

Almost surely, 2^40001556 is an apocalyptic number.

It is an amenable number.

40001556 is an abundant number, since it is smaller than the sum of its proper divisors (70354284).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

40001556 is a wasteful number, since it uses less digits than its factorization.

40001556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16464 (or 16462 counting only the distinct ones).

The product of its (nonzero) digits is 600, while the sum is 21.

The square root of 40001556 is about 6324.6783317415. The cubic root of 40001556 is about 341.9996238155. Note that the first 3 decimals are identical.

The spelling of 40001556 in words is "forty million, one thousand, five hundred fifty-six".