21155370 has 32 divisors (see below), whose sum is σ = 50960448. Its totient is φ = 5620608.

The previous prime is 21155369. The next prime is 21155371. The reversal of 21155370 is 7355112.

It is an interprime number because it is at equal distance from previous prime (21155369) and next prime (21155371).

It is a self number, because there is not a number n which added to its sum of digits gives 21155370.

It is not an unprimeable number, because it can be changed into a prime (21155371) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8062 + ... + 10358.

It is an arithmetic number, because the mean of its divisors is an integer number (1592514).

Almost surely, 2^21155370 is an apocalyptic number.

21155370 is an abundant number, since it is smaller than the sum of its proper divisors (29805078).

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

21155370 is a wasteful number, since it uses less digits than its factorization.

21155370 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2614.

The product of its (nonzero) digits is 1050, while the sum is 24.

The square root of 21155370 is about 4599.4967115979. The cubic root of 21155370 is about 276.5711497502.

The spelling of 21155370 in words is "twenty-one million, one hundred fifty-five thousand, three hundred seventy".