20921428 has 48 divisors (see below), whose sum is σ = 41827968. Its totient is φ = 9072000.

The previous prime is 20921419. The next prime is 20921429. The reversal of 20921428 is 82412902.

It is a super-2 number, since 2×20921428² = 875412299118368, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 20921396 and 20921405.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20921429) 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, 115498 + ... + 115678.

It is an arithmetic number, because the mean of its divisors is an integer number (871416).

Almost surely, 2^20921428 is an apocalyptic number.

It is an amenable number.

20921428 is a deficient number, since it is larger than the sum of its proper divisors (20906540).

20921428 is a wasteful number, since it uses less digits than its factorization.

20921428 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 304 (or 302 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 28.

The square root of 20921428 is about 4573.9947529485. The cubic root of 20921428 is about 275.5479015920.

The spelling of 20921428 in words is "twenty million, nine hundred twenty-one thousand, four hundred twenty-eight".