400155551 has 2 divisors, whose sum is σ = 400155552. Its totient is φ = 400155550.

The previous prime is 400155517. The next prime is 400155577. The reversal of 400155551 is 155551004.

It is an a-pointer prime, because the next prime (400155577) can be obtained adding 400155551 to its sum of digits (26).

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 400155551 - 2¹⁰ = 400154527 is a prime.

It is a super-2 number, since 2×400155551² = 320248929992227202, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 400155551.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (400155451) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 200077775 + 200077776.

It is an arithmetic number, because the mean of its divisors is an integer number (200077776).

Almost surely, 2^400155551 is an apocalyptic number.

400155551 is a deficient number, since it is larger than the sum of its proper divisors (1).

400155551 is an equidigital number, since it uses as much as digits as its factorization.

400155551 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2500, while the sum is 26.

The square root of 400155551 is about 20003.8883970092. Note that the first 3 decimals coincide. The cubic root of 400155551 is about 736.9017964809.

The spelling of 400155551 in words is "four hundred million, one hundred fifty-five thousand, five hundred fifty-one".