400136621 has 2 divisors, whose sum is σ = 400136622. Its totient is φ = 400136620.

The previous prime is 400136567. The next prime is 400136651. The reversal of 400136621 is 126631004.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 346480996 + 53655625 = 18614^2 + 7325^2 .

It is a cyclic number.

It is not a de Polignac number, because 400136621 - 2⁶ = 400136557 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (400136651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 200068310 + 200068311.

It is an arithmetic number, because the mean of its divisors is an integer number (200068311).

Almost surely, 2^400136621 is an apocalyptic number.

It is an amenable number.

400136621 is a deficient number, since it is larger than the sum of its proper divisors (1).

400136621 is an equidigital number, since it uses as much as digits as its factorization.

400136621 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 400136621 is about 20003.4152334045. The cubic root of 400136621 is about 736.8901761906.

Adding to 400136621 its reverse (126631004), we get a palindrome (526767625).

The spelling of 400136621 in words is "four hundred million, one hundred thirty-six thousand, six hundred twenty-one".