155215421 has 4 divisors (see below), whose sum is σ = 155792700. Its totient is φ = 154638144.

The previous prime is 155215409. The next prime is 155215433. The reversal of 155215421 is 124512551.

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

It is an interprime number because it is at equal distance from previous prime (155215409) and next prime (155215433).

It can be written as a sum of positive squares in 2 ways, for example, as 77246521 + 77968900 = 8789^2 + 8830^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-155215421 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 (155215441) 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, 288236 + ... + 288773.

It is an arithmetic number, because the mean of its divisors is an integer number (38948175).

Almost surely, 2^155215421 is an apocalyptic number.

It is an amenable number.

155215421 is a deficient number, since it is larger than the sum of its proper divisors (577279).

155215421 is an equidigital number, since it uses as much as digits as its factorization.

155215421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 577278.

The product of its digits is 2000, while the sum is 26.

The square root of 155215421 is about 12458.5481096314. The cubic root of 155215421 is about 537.4172748836.

Adding to 155215421 its reverse (124512551), we get a palindrome (279727972).

The spelling of 155215421 in words is "one hundred fifty-five million, two hundred fifteen thousand, four hundred twenty-one".